
You might try asking over at Cemetech or Omnimaga, there are a lot more people there who could probably help you out. Have you tried running games or anything on it? If games run fine, it might be that your OS got corrupted somehow. But personally i think you'll have better luck figuring it out at one of the other two sites.
Btw, when you say you've tried resetting the OS, do you mean the OS or the archive memory? Have you tried resending an OS? And what is the cache you're talking about?