Why Does My Computer Crash When I Am Not Doing Anything Extra Ordinary?

There could be a virus. Run a virus scanner like AVG and see if it picks anything up. If that doesn't do anything, go to Start -->Control Panel-->Performance and Maintenance-->System Restore(Which is on the left side) according the Windows XP. With System Restore, you can turn your computer back to an earlier date. Like let's say your computer worked just fine a few days ago. You can choose a date that has been set to the day before your computer started acting up, and everything should be just fine after it's completed. It doesn't delete anything, though you may find that some programs you may have installed during that time may be gone or some programs you've deleted may show up again, but personal files sucks as music and photos will not be touched.