Restart the computer and immediately start pressing the F8 key, once per second, till a selection screen loads. Use the up/down arrows on the keyboard to select "Safe Mode", then press the "Enter" key.. Once in Safe Mode, click on Start-All Programs-Accessories-System Tools-System Restore..

At the SR window, select "Restore my computer to an earlier time", then click on the "Next' button. At the next "Calendar" window, select a bold date just prior to the date of the problem, click on "Next", then follow the prompts to restart the computer and go back to a day when things were good.

Hope this helps.