Easiest way is to the control panel and open up the back up and restore section. inside you will see "Recover system settings or your computer" click on that. You will then see a button "Open System Restore" - click on that. This opens a dialog that will allow you to chose a time in the recent past - hopefully before you were experiencing issues and restore to that time. It will not destroy your personal data but will reset your system settings to a time before you were having problems.
DW