I dont expect a intelligent answer because i cant give you an intelligent question at the moment. I was playing an mmorpg and out of the blue i crashed to the desktop..that has never happened to me before. I was on ventrilo and i crashed out of ventrilo as well. I tried getting BACK into ventrilo and for about 15 mins I wasnt able to. When i did get back in all my sound settings were gone. I fixed my sound setting then went back in game..about 5 mins later i crashed again and BRIEFLY saw a blue screen. I have scanned and defraged and there is nothing wrong... my programs say. Today when i got on and the pc booted up to the desk top I got a MESSAGE that said something like the registery has been changed and my system used a back up to RESTORE the registry and that it was successful. The pc is just not acting like it did...something is wrong...and I have no idea where to start to look. Do you?
I am so sorry for being so vague, I usually come here with enough info for you but this time Im at a loss.do system restore and see if that fixes it heres how.

http://support.microsoft.com/kb/306084

follow the link above..

System Restore Will Help , If not you could Try Full System Restore (( RESETTING to factory Settings ))