There could be a number of issues, but it sounds like it may be a problem
with hard drive itself.

Try running a disk check on the problematic drive(s) and see if that helps
solve the problem.

Interestingly, the drive was fine. We finally had to perform a clean
install of Windows Vista which resolved the problem. We really get
frustrated with Microsoft Windows. It is one of the most unreliable pieces
of software imaginable. Without fail, everyone of our systems needs a clean
re-install of Windows every 12 to 18 months.

We have high-quality UPS battery backups and surge suppressors, current
security suites, and good routines for running check disks. Yet, we still
have to restore corrupt Microsoft operating systems routinely. The rebuilds
are extremely costly to us, but the trouble-shooting before hand (to try and
avoid a rebuild) is just as costly.

Not a happy camper!


***********
> There could be a number of issues, but it sounds like it may be a problem
> with hard drive itself.
>
> Try running a disk check on the problematic drive(s) and see if that helps
> solve the problem.