Tried to upload zip files to the main site?

I tried a couple of times to use the feature of uploading zip files to the main site, but it keeps telling me that the file is not "a valid zip file", which, needless to say, it's not true by all conventional means.

Anybody cares to offer a hypothesis?

Can you email me the zip file ( girlswithmuscle@gmail.com ) ? That way I can try to diagnose what the problem is.