The problem is in the download itself there is nothing wrong with your system.
Here is a possible solution:
1. Download 2 or 3 copies of the full program (200mb+) from different sites. 2. Unzip the first to a temp directory. 3. Copy the error log generated and paste it into Wordpad. 4. Open both copies in its own zip program (2 seperate sessions). 5. Scroll through the error log in Wordpad until you find an error. 6. Then try to extract just that file from each of your copies until you get a clean extract. This may take several tries even in the same download. 7. Repeat steps 5 and 6.
I have gone through this process about a dozen times. This includes the AAFiles download which they claim is free from errors. This does work, but I am still ordering the game on CD (with luck it is not corrupt).