What is the manufacturer, make, and model of your computer?
Do you know when this problem began? Try a System Restore to a point in time BEFORE the problem began. Here's the procedure: http://www.vistax64.com/tutorials/76905-system-restore-how.html. Be sure to check the box to show more than 5 days of restore points. If the first attempt fails, then try an earlier point or two. NOTE: You will have to re-install any software and updates you installed between now and the restore point, but you can use Windows Update for the updates.
I hope this helps. If not, knowing your computer will help us find a possible solution from the company website and there are many other options we can try - but if this just started, this option is the best and simplest to try first. Post back and let us know what happened and the information about your computer.