Sounds like registry corruption to me. What operating system? If it's Vista or Win 7 boot to the advanced options menu by pressing F8 during restart. At the advanced options menu choose "Repair Your Computer" XP will not have that option. In XP you could try Booting to the advanced options menu and simply choosing "Safe Mode" see if a restore can be done from the safe mode.

I think the first thing I would have done was go to system restore and done a quick restore to the day before when all was well. You could still do that actually and that would restore the settings to the correct ones. If it happens again do that first just select a time/date from a day just prior when everything was ok. Go to Start Select All Programs Select Accessories Select System Tools Select System Restore here is a good site with info on system restore in Vista http://www.5starsupport.com/faq/vista-system-restore.htm I am wondering if this somehow could have had something to do with the original dates for daylight savings time? It was originally set to occur Sunday April 6th but this year of course it was changed. There was a patch put out through windows updated to fix this issue. It just seems strange it happened so close to that date. Do you have all your current windows updates done?

You might open the Computer Management window and then look in 'Services for 'System Restore. Then see if it is set as automatic, check the dependencies tab and expand what is there. Think you will see it requires the 'Service named 'RPC' to also be running. you might also check; Right click myComputer Select Properties You should see a tab for System Restore. Is it turned on ?

Doing a restore simply means restoring back to a date prior to your error problems hopefully fixing the issue, and can be undone if you choose, so no harm no foul.