Alright, let's not waste any time. We need to perform a System Restoration, which will hopefully fix the issue. Click on Start -> All Programs -> Accessories -> System Tools -> System Restore. A new window will appear. Make sure that "restore my computer to an earlier time" has a bullet point next to it, and click next. You will now see a calendar. I want you to go back to yesterday. When you click on the day, you will see a list of times. Pick the one that best suits you. Click on next. You will now see a confirmation screen. Confirm that the date and time are correctly set, and click on finish. Your computer will now restart. Just before resetting, you will see a progress meter, showing you the restoration process. It may take a few minutes, so be patient. The computer will then restart, and with any luck, when you login, you will be back to normal. Good luck to you.