Question : C: drive not accessable

I'm cleaning a highly infected Dell Dim. and while I've been able to deal with most of the problems the infections have caused in Windows, there's one that has me stumped.

It had various fraud anti-virus/antispyware trojans as well as vundo, smitfraud and bunches more. Most of the bad stuff is gone, now. It was shutting down due to DCOM problems - I just told the PC to take no action. Updates were disabled (still only at SP2 right now), but that has been fixed. I've been scanning with Malwarebytes, spybot s&d, and Trojan remover (so far).

The final major problem is that I can't access the C: drive. When I click it in Win Explorer I get the following error: "C:\  is not accessible. Access is denied." I checked in Computer Management and the C: drive isn't listed as a storage device. I've run various security repair programs & files without resolving the problem. I've run the Dell disk diagnostic and the DFT disk diagnostic and both claim no problems with the drive. I found a couple of 'HDD repair' programs (for fixing problems post-infection) and both of them reported that there is nothing to fix. CHKDSK /R has been run in repair console and while there I ran a DIR command. The result is that out of approximately 55GB, there is one GB free.

Hope one of you experts has an idea to resolve this (short of reinstalling XP).

I'll be back here in about four hours - about 10:00 Eastern. Talk to you later.

Answer : C: drive not accessable

personally, i would also install xp - but if you like to keep trying; that's your decision
i take it you took ownership of the drive : http://support.microsoft.com/kb/308421
also; at any point, did you run sfc /scannow to repair the system files?
or a repair install :  http://www.michaelstevenstech.com/XPrepairinstall.htm