Unfortunately, I cannot provide an answer, but only can confirm the same
problem on my Windows Home Server machine. Shut down and reboot "sometimes"
fixes it, but not always.
This article seem to take "partially" care of it, but does not really give a
On my machine one time it was so bad, WHS created a new Adminsitrator
account (which is the only account that let's you access the machine!) and
basically reset all my data!
I only was able to put the HDD in another machine, and copy my "old"
Administrator account into the new Administrator account folder!
BTW: It is a new HDD and scandisk does not report any problems with the
disk. The S.M.A.R.T. values (as read out with Speedfan) do also not reveal
any clue about why it should happen!