Are you sure its clean ????

I have seen machines act up when it cant get updates...depending on the OS...

MS has a doc how to open the requests on the ISA\firewall ...as they changed the update site...

The machine will continually try and connect and starts to misbehave when it cant

Mostly I have experieinced this with W2K machines...

Sometimes....its just best to format and reinstall...that way you may be able to glean if it is a hardware issue..

Installs will usually fail with faulty hardware

MLF