I downloaded a zip file and tried to extract it (on Windows 7)
An unexpected error is keeping you from copying the file. If you continue to receive this error, you can use the error code to search for help with this problem.
Error 0x80004005: Unspecified error
I copied the file to a linux machine and tried to unzip there – for every file in the archive, the message was
skipping: FILE need PK compat. v6.3 (can do v4.6)
At that point I realized this is some advanced zipping that windows default extraction can’t handle. I fired up 7zip and had no problem extracting right away!