1. It's possible that your computer may have so many background programs running that there is not enough main memory to run your main programs. All icons in your computer's system tray are background programs using memory.
To see and remove all running background programs:
a. Press the Ctrl + Alt + Delete keys at the same time.
b. Click any program or task except Explorer or Systray,
c. and then click End Task.
Repeat steps b and c to quit all programs except Explorer and Systray which are necessary components of Microsoft Windows.
You should now have a clean system. If you don't want any background programs starting when you boot, use the Start/Search function to find the program and either configure it not to run, remove it from Programs/Startup, or delete it from your system.
2. Your hard drive could be too full of data to function efficiently. There should be at least 2MB-3MBs (200,000 -300,000 bytes) of free space to allow for disk file chores. Note that this mostly applies to the C: drive or whatever drive your Window's cache is on.
If your C: drive is too full, delete unused programs on the C: drive to make space.
3. Your computer could have a fragmented hard drive. This results from programs being loaded and deleted. Run the Window's hard drive defragmenter (Defrag) once a month.
4. If you have 64 MB of memory or less, or you like to play games, you may not have enough system memory to run your software efficiently. You should probably upgrade to 128MB or more of system memory.
5. You could have old or conflicting Windows device drivers. An example would be you might actually have two entirely different video drivers on your system and Windows could actually be alternately using both of them.
To prevent this problem, First boot the computer in Safe Mode by pressing and holding the F8 key during startup, after the DOS memory check has completed.
While in Safe Mode select Start/Settings/Control Panel/System/Devices. Click on all the devices and see if the various drivers have any yellow or red exclamation marks (which indicates a driver conflict) and also determine if there are any duplicate drivers that can be eliminated.
You may have to delete and reload a driver to correct these problems. Duplicate drivers can and should be deleted.
6. As each new Windows program is installed and uninstalled, it leaves behind parts of itself that can slow down or crash your computer. These are mostly .dlls and other shared files.
It's also very possible when uninstalling a program that needed Windows system files can be deleted. When your computer asks if you want to uninstall shared files it's usually safest to say no -- even if your uninstall program claims the files are not being used.
Old Windows drivers can be found by booting into Safe Mode, then opening Control Panel/System/Devices and ridding your system of old drivers.
Another option is to use Noton Utlities' WinDoctor program to find and fix problems. Usually Norton Utilities can be downloaded for a free 30 trial at www.symantec.com.
Otherwise, the only real answer to this problem is to reload Windows into a new directory which elimainates all old junk and leftover files. This is something to do last, as you will also have to reload all your Windows settings, drivers, and programs.