Did you load the OS from scratch? Blank? etc?
A damaged OS can burn a tech's day or week fast.
I work with seniors to get them onto the internet - one recently rec'd a computer that has been sitting since 9/08. Can only boot in safe mode. Tried SFC SCANNOW but got RPC Server error 1084 - but cannot turn it on from safe mode. It had SP2 - I loaded SP3. My brain is fried (been at it all day). Have tried three restore points - all took but no improvement.
Would reverting all the drivers help? All the seniors want is to play POGO - basic internet, email.
Computer is a DELL INSPIRON 8600