That's odd!!!!

Here is the situation.
It's a customer's pc, the process is done by phone.
It's a 2000 that boots fine, with a message that "Windows fixed the Page File Size blah blah blah...".(Which makes sense if u read the following)
The weirdest part is, I cannot access "C:".Either by Windows Explorer, or DOS.When in DOS, I can navigate through folders, but not to "C:".I get the "Access Denied" error(Both Explorer or DOS).Right Click>Properties, File System : Unknown(!!!).Size 0GB Free space 0GB.
Chkdsk in read-only mode returned no error messages.
Logged in as Administrator.
There's also the "D:" partition which works fine.
Disk Management shows the disk to be in good condition.
It's a Maxtor 20GB about 6 years old.
It seems to me as an OS situation here.
Could it be a virus, or a 3rd party app that caused this?

Is the partition NTFS format perhaps hence the issue with DOS and have you checked either via FDISK or a the likes of partition magic the actual partition set up.It could have some weird set up where the OS is on the extended partition or some ilk [i.e. wheres the windows folder installed]?
Perhaps the customer has somehow renamed the drive [from c: to d:]?

Thx for the reply.
I've found this
http://support.microsoft.com/kb/315270/
It's the message that comes up.
Told him to try it out for the moment.
It's a school lab, so anyone could mess it up...

In case the System account is deleted, could it be recreated somehow?

Open a command window and type "net user" at the prompt.If done with admin status this will list all the user accounts on the system.


http://img54.imageshack.us/img54/1909/netuserct9.png

You could also try using Knoppix or Ubuntu from a live CD and see if you can access the OS that way.