Windows Vista unable to boot – ekgknn.sys corrupt/missing

Hi!

I have been passed a laptop with Vista Home from my boss (non-work PC from a relative!) that appears to be infected with a fake AV product. After a few passes of legitimate free AV software and removing the autorun entry in msconfig the fake AV was inactive… a few reboots later and it was back!

I disabled the autorun entry in msconfig again and rebooted. When I got a chance to return to it later there was a BSOD. Vista recovery DVD cannot repair, complaining of a critical boot file: ekgknn.sys being corrupt/missing.

I cannot find any mention of this file on Google or Bing, which seems very unusual. Any ideas?!?

Thanks in advance!
Stephen.