You should open an elevated command prompt and type the command line I will put in BOLD below.
[I cannot recall if you have to restart the system afterwards - I don't think you need to...]
assoc .zip=CompressedFolder
Also - if you open things other than ZIP - I would like to suggest "7-Zip" as a great free utility to use for opening/creating all sorts of compressed files.
Please come back and let everyone know if you got things sorted out!