Originally Posted by William_Wilson
did you install anything recently? Anything at all, updates, apps, etc - from a possibly non-legitimate source?
For it to affect your system this badly it sounds like data corruption or possibly a root kit (trojan-like software)
Like William said, have you ever installed any weirdo software (or using cracks) recently? It is possible you could been infected that way. Anyway, can you just download HijackThis
and run HijackThis and post your log here for us? For automated suggestions, use this site: HijackThis Logfileauswertung
(Don't worry it's in English, even if it's in German language, I think you can understand it)