Error: Unable to run AutoCAD

This is one of the toughest scenarios that we get into Product Support and there hasn't been a definitive solution is this error:

Unable to run AutoCAD. This may be due to one of the following reasons: 
1) This version of AutoCAD was not installed properly. 
2) You do not have sufficient rights to run AutoCAD.

This is a screen capture from Windows XP.

We recently had a case in which the error was happening on Windows 7.  The user was running AutoCAD 2010.  During the installation of Windows 7 Service Pack 1, the system hung and had to be rolled back to its previous state. After the rollback, AutoCAD ceased to work.  The user just re-applied the Windows 7 Service Pack 1 and the issue was resolved.

The suggestion is to apply a Service Pack to your Windows computer if you are getting this error otherwise, you will need to reinstall the operating system.

Thanks to Steven Costa for this tip.