This program will tell you whether your hard drive is working properly. Sometimes, errors reported here are fairly meaningless, but other times, Scandisk will find files, and even entire directories, with nasty problems. Delete all temp files. Delete all of these files. Run a virus scan.
Many companies offer free trial versions of their virus scanning programs on the Web.
Viruses can wreak havoc on your system. Restart the system and see if you're still having trouble. Many times, these simple steps will pinpoint problems relating to slow systems, crashes, and weird behavior. Of course, these files are a bit more complex, so you should know what you're doing before playing with them. Online Windows Tips . . .