Error "Unable to run AutoCAD"

After having had Civil 3D 2010 up and running for a while, mainly as AutoCAD 2010, I got an error message about Base.dcl not found when starting the full Civil 3D. This was not when I started Civil 3D as AutoCAD 2010. I tried to solve that by repairing, but the base.dcl-error stayed. Also reinstalling did not work. Then I tried uninstalling and reinstalling from the deployment. It didn't solve the problem. Then I tried uninstalling and removing everything that comes from Autodesk, such as Design Review, and reinstalling from the original disks. No result. Untill then I had the "AutoCAD Civil 3D as AutoCAD" working. At some point I could no longer remove the software, so I started deleting all files by hand. I even started Windows in Save mode to get rid of the dll's in the common directory. So I thought my computer was quite clean.

After reinstalling from the CD's now I get the following message, also when I start Civil 3D as AutoCAD 2010:

"Unable to run AutoCAD. This may be due to one of the following reasons:
1) This version of AutoCAD was not installed properly. In this case, you may wish to reinstall AutoCAD.
2) You do not have sufficient rights to run AutoCAD."

The latter is not the case, so the advice is to reinstall AutoCAD, which I've been doing all day yesterday.

So, desperate as I am, I finally went to this forum. Please can someone help?

Some details:
- I was running perfectly before I ran in troubles
- It's on Windows XP Professional 2002 SP3

Sounds like a windows users account is corrupt. Try creating a new user on the pc, install with full admin rights, all anti virus software off and then see if that user account can run it.

Problem solved!

There is an old trick that came to my mind: switch off your anti-virus software (PC Doctor in my case) and try again. More than 24 hours later I have it all working again. It would have been nice if there were some better error messages during installation....

Pfff.

P.S. I just see your reply now J.Murphy. You had the same tip about the anti virus software. Thanks!