Since nothing else seems to work, I would try either hooking the disk up as a slave
on another PC, or booting from a BartPE CD such as UBCD4WIN
and then running a chkdsk on it. Clearly something in the existing operating system
setup is getting in the way (probably a device driver) so the suggested method(s)
would circumvent that. The alternative is to disable various device drivers that
might be getting in the way, but without a lot of further information I am loathe
to recommend that course of action. Hope this helps. Cheers. Spexx.