Try checking your hard drive for errors then run tune up. How to perform disc error checking - http://support.microsoft.com/kb/315265 If the defragger will not run in tune up after checking your hard drive for errors please contact support. How to reach support - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
Jim - MVP Windows Live - Forum Moderator - Live One Care - Live Mesh - Microsoft Security Essentials