Here is a list of possibilities that can be causing this problems...
BAD MEMORY MODULES. Try inserting the command DEVICE=C:\WINDOWS\HIMEM.SYS /TESTMEMN into your CONFIG.SYS file with the System Editing utility and watch your computer for a message ?HIMEM has detected unreliable memory at address xxxxxxxxx? which will certainly indicate that there is a memory problem. It may take several reboots over a period of days for this to show up. You can also download diagnostic software from AMI, or DocMemory from SIMMTester.com, to test your system?s memory.
BAD VIDEO DRIVERS. Check with your video card manufacturer for an updated set of drivers. If they don?t have an update, check one of the driver sites here.
CPU, BUS SPEED OR MULTIPLIER OVER CLOCKING. DON?T!
FAULTY OR DIRTY COOLING FANS ON YOUR CPU OR POWER SUPPLY. The CPU fan can be cleaned with a small paintbrush and some compressed air. The power supply fan should be cleaned only by someone who is comfortable working around high voltage capacitor components. (If you are not sure if this is you ? then trust me ? it isn?t you.)
GRAPHIC ACCELERATION IS SET TOO HIGH. Right-click My Computer, select Properties, then the Performance tab, then the Graphics button. Turn down graphics acceleration a notch, reboot, try again. Repeat as necessary.
ANIMATED MOUSE CURSORS, MOUSE TRAILS, AND ACTIVE DESKTOP can also rarely cause these kinds of problems. Try disabling them all and re-adding one at a time until you find the culprit.