This was a tough virus. The symptoms:
Cannot access the C drive. When you click on My Computer you don't get any results.
Cannot access any external drive. D, USB flash drives, external hard drives, etc.
Cannot access Regedit. This produced an admin privilege error.
Cannot access All Programs. This would show a gray box where you would normally see your programs and then the PC would lock up.
Cannot access the internet.
Cannot run programs such as Malwarebytes or SuperAntispyware. System would either lock up or the programs would just not run.
It almost seems like the user privileges to read/write directly to external drives was disabled.
Oddly enough, these functions were OK.
Right-click on My Computer to select Manage.
1) Backup data. Since the virus was somehow blocking access to the DVD writer as well as to any external drives, I was not able to copy any data off the system. So I created an Ubuntu boot disk and rebooted the system from the CD drive. From there I could copy the user data to an external drive without any problem.
2) Ran SDFix from Safe Mode. I was able to get SDFix onto the affected PC by opening a DOS window and copying the SDFix.exe file to the Desktop by using the command line.
After running SDFix Regedit was now usable and the system could also get onto the internet.
3) Ran ComboFix. I copied the file over to the PC in the same was as above, using the DOS window. ComboFix found a LOT of viruses and was able to clean them up nicely.
After that I was able to run Malwarebytes from Safe Mode as well as Super AntiSpyware. I could only use the Administrator logon as the user account was still having problems with executing programs and creating files on the C: drive.
Instead of fighting with that original account I decided to create a brand new account and that seemed to work OK. The new account is able to function properly.