--Marvel Origins Set Database
--Spider-Man vs. Doc Ock Starter Set Database

the zip files contains invalid archive. I tried using Winzip, Pkzip, and WinRar but I can't open the files.

I have the same problem with mine
:angry:

Works fine for me here, tried on several different PCs, and other people are able to install.

If you have an anti-virus program it might be interfering.

The zip files were created using the built-in Windows XP folder compressor. All of my beta-testers were able to use them over the last several weeks.

I had that problem when I downloaded the big zip file and the small one at the same time.. or while doing a lot of stuff at once. So I deleted it and redownloaded the file and it worked fine for me.