Error 0x80040707

I know, TechRepublic has already made a solution to the notorious error code 0x80040707. Alas, it did not solve my problem. I have visited hundreds (no joke) of sites trying to resolve this issue, everywhere from starting up in Safe Mode to registry edits (none had a bad effect, but none worked). I receive Error Code 0x80040707 Description: Access is Denied!. Well, there is apparently no override and I am still stuck for an answer. It occurs when trying to install Command and Conquer Generals (which I have installed countless times before) and only on CNC Generals. Can anyone help?