1. Panayiotis Christodoulou

2.  I have problems in Windows after installing new software  How do I fix illegal operations?  My computer is running slow what steps can I do to fix it?

3.  If you are encountering problems with your computer or other programs after installing new software on your computer, uninstall the program and see if the issues persist. After the program has been uninstalled, try installing the program again.  If, after installing a program, you're unable to boot into Windows, try booting into Safe Mode.

4.  If you continue to experience issues, check the software manufacturer' website for any updates to the program, game, or utility you are installing.  If you're installing a software program or drivers for a hardware device, such as a printer, get the latest software and drivers from the manufacturer instead of using the included software. See our drivers page for links to different types of hardware drivers.

5.  When the operating system or computer processor receives an instruction from a program that it does not recognize and cannot process, it may issue a command known as an Illegal Operation. Below are reasons why an Illegal Operation happens on a computer.

7.  TSR's or third-party programs running in the background are one of the more commonly found reasons for Illegal Operations. If the Illegal Operation is happening when running a game or program close all other open programs and TSR's running in the background.  Removing a TSR in Windows 2000 to Windows 7  Press and hold CTRL + ALT + DEL, then click the Task Manager option. Or if you're running Windows XP, it should immediately open the Windows Task Manager window. Within Task Manager, click the Applications Tab, select the program that you want to end, and click the End Task button.

8.  As can be seen in the above picture, the Applications window only displays programs that are currently open and visible to the user. Other TSRs and Windows Processes are shown in the Processes tab. Clicking on the Processes tab displays each of the processes running and the system resources they're using, as shown below.

9.  We recommend you only End Process for programs you know. If you are unsure what a process is, doing a search will return the results of each process.

10. Error in program coding Verify that the program causing the Illegal Operations is compatible with your version of Windows and check with the developer to make sure no patches or updates are available. There is no such thing as a perfect software program, and it is not uncommon for multiple patches and updates to be released during a program's life cycle.

11. Data is not being read properly from source When running a program or game from a CD you receive an Illegal Operation, verify that the CD is clean. If you are running a game from a floppy diskette or other drive make sure the disk or drive does not have physical errors with it by running a Scandisk.

12. Corrupt files Corrupt, bad, or missing files can cause Illegal Operations. Try uninstalling and then reinstalling the program causing the Illegal Operation to verify that any corrupt, bad or missing files are replaced or repaired during the reinstallation.

13. Memory managers If you are running a memory manager, it is recommended you temporarily disable or uninstall this program to verify it is not causing the Illegal Operations.

14. Bad, incorrect, or outdated video drivers Bad, incorrect, or outdated video drivers can cause Illegal Operations when moving the mouse, highlighting, or when high demands are placed onto the video card. Try decreasing the resolution to make sure your current settings are not causing the problem.

15. Computer virus Because computer viruses and other malware load into memory and can improperly modify files they can cause Illegal Operation error messages. Make sure an anti- virus protection utility is installed on the computer and that it is up-to-date.

16. Added hardware If new hardware has been recently installed (e.g. computer memory) in the computer it or any drivers that had to be installed may be conflicting with other computer hardware. Temporarily remove any new hardware and the software associated with it to make sure it is not causing the problem.

17. Bad Memory, invalid bits or physically bad memory Bad memory can cause Illegal Operations. If you have recently added memory to the computer, remove the memory to make sure it is not causing the problem. If no memory has been recently added and you have tried all the above recommendations, test your computer memory.

18. Corruption or problem within Windows Because Windows controls the memory operations and all system operations if any part of Windows is corrupt it can cause Illegal Operations. If you have tried all the above suggestions, we suggest reinstalling Windows.

19.  Reboot If your computer has not been rebooted recently, make sure to reboot it before following any of the steps below.

20.  Background programs One of the most common reasons for a slow computer are programs running in the background. Remove or disable any TSRs and startup programs that automatically start each time the computer boots. If you have an antivirus scanner on the computer, spyware protection program, or another security utility, make sure it is not scanning your computer in the background. If a scan is in progress, it can decrease the overall performance of your computer. If this is the case, allow the scan to complete, and the computer's performance should improve.

21.  Delete temp files As a computer runs programs, temporary files are stored on the hard drive. Deleting these temp files can help improve computer performance. First, we suggest using the Windows Disk Cleanup utility to delete temporary files and other files no longer needed on the computer.

22. Unfortunately, the Disk Cleanup may not delete every file in the temp directory. Therefore, we also suggest deleting temporary files manually. To do this, open the Start menu and type %temp% in the Search field. In Windows XP and prior, click the Run option in the Start menu and enter %temp% in the Run field. Press Enter and a Temp folder should open. You can delete all files found in this folder and, if any files are in use and cannot be deleted, they can be skipped.

23.  Free hard drive space Verify that there is at least 200-500MB of free hard drive space. This available space allows the computer to have room for the swap file to increase in size, as well as room for temporary files.

24.  Bad, corrupted or fragmented hard drive Run ScanDisk, chkdsk, or something equivalent to verify there is nothing physically wrong with the computer's hard drive. Run Defrag to help ensure that data is arranged in the best possible order. Use other software tools to test the hard drive for any errors by looking at the SMART of the drive.

25.  Scan for malware Today, spyware and other malware is a big cause of many computer problems, including a slow computer. Even if an antivirus scanner is installed on the computer, we recommend running a malware scan on the computer. Use the free version of Malwarebytes to scan your computer for malware.

26.  Scan for viruses If your computer is infected with one or more viruses, this can cause your computer to run slow. If your computer does not have an antivirus program installed, you can run Trend Micro's free Housecall online utility to scan for viruses on your computer, as well as remove them. It is also recommended that you install an antivirus program for active protection against viruses.

27.  Hardware conflicts Verify that the Device Manager has no conflicts. If any exist, resolve these issues as they could be the cause of your problem.

28.  Update Windows Make sure you have all the latest Windows updates installed on the computer. If you are on the Internet when your computer is slow, make sure all browser plugins are up-to- date. You can also try disabling browser plug-ins to see if one of them is causing the slowness.

29.  Update your drivers Make sure you have the latest drivers for your computer hardware, especially the latest video drivers. Having out-of-date drivers can cause an assortment of issues, including slow performance.  Reboot computer again If you have done any of the above steps but your computer is still acting slow try rebooting the computer again at this point.

30.  Memory upgrade If you have had your computer for more than two years, you may need more memory. Today, we suggest computers have a minimum of 1GB of memory (RAM) for 32-bit system and 2GB for a 64-bit system. By having enough memory for programs to run within memory, your computer will not need to swap information stored in memory to the swap file. If the hard drive light is constantly active, it can be an indication the computer is frequently swapping information between your memory and hard drive.

31.  Hard drive upgrade SSD One of the biggest bottlenecks of a computer is the hard disk drive. For anyone with a slow computer or just looking for the best component to upgrade, upgrading from a hard drive to a Solid State Drive (SSD) can significantly improve the performance of a computer.

32.  Run Registry cleaner We normally do not recommend Registry cleaners. However, if you have followed all of the above steps and your computer is still slow, try running a Registry cleaner on the computer.

33.  Computer or processor is overheating Make sure your computer and processor is not overheating. Excessive heat can cause a significant decrease in computer performance because most processors automatically reduce the speed of the processor to help compensate for heat-related issues. Dust, dirt, and hair can also constrict proper airflow inside your computer, which can cause a computer to overheat. Make sure your computer case is clean and fans are not obstructed.

34.  Erase computer and start over If none of the above solutions resolve your issues, another option is to either reinstall Windows or erase everything and then start over. Erasing everything and starting over can increase performance by getting rid of old software or drivers that may be on the computer and causing the computer to be slow. Installing a fresh copy of Windows, software programs, and the latest drivers help verify there are no software related issues causing your computer to be slow.

35.  Hardware issues Finally, if your computer is still slow after trying all of the above recommendations, there may have a more serious hardware related issue, such as a failing component in the computer. Examples of failing hardware could include a failing or bad hard drive, CPU, RAM, motherboard, or another component. You can run hardware diagnostic tests using the Ultimate Boot CD (UBCD) utility. This utility provides many diagnostic tests that you can run and determine if your computer has a bad piece of hardware.

36.  Old computer If your computer is more than five years old, the age of the computer could be the cause of the slow performance. As more advanced software programs are released, they are optimized to run more efficiently on newer computers. Older computers are not able to run these new programs as well, which can cause them to perform more slowly. We recommend that you consider purchasing a new computer or accept that your computer is not going to be as fast as a newer computer.