Did it always have this problem, or did the problem recently start?
1. click start, bottom left of you screen
2. click all programs
3. click accessories
4. click system tools
5. click system restore
6. click the box that says: restore my computer back to an earlier time, click next
7. click a bold date on the calender, a date before the problem started, click next
8. follow the directions to set the computer back to an earlier time, before the problem started.
Wait until the system is restored, restart the computer, does it work correctly now?