HOW TO.....

Unzipping Files On a Mac Using Unarchiver

The Unarchiver is a third party tool that can be thought of as a swiss army knife of compression formats, able to work with virtually any archive file format you can throw at it. It works in much the same way as the default Archive Utility, only running when an archive is encountered, which it quickly decompresses then quits again. As such, it can also be used to forcibly extract problematic zip/cpgz files:

 

Step 1:

Download The Unarchiver for OS X and install it, make sure it associates with all archive formats.
Use this link: Unarchiver

Step 2:

Open the problematic .zip or .cpgz file (generally focusing on the original zip is best) through Unarchiver and let it decompress.

The archives files should now be accessible as intended.

See Screen Shots Below

unarchiver

unarchiver 2