Is there a solution to the zip/cpgz cycle after downloading from Dropbox to Mac?

Solution 1:

First does this happen with all zip files or just this one?

If it is just this one you might try using an alternative free zip expanding utility (For Example Stuffit Expander) http://www.smithmicrosoftware.com/stuffit-expander.html

Sometimes renaming the ext from cpgz to .zip helps.