My Zip files aren't unzipping
I receive PDF-zipped files for work via email attachments, but when I double click on them, the window disappears (a brief flash of a message saying the file is being "archived" flashes, but then nothing.) When I go to my user>library>maildownloads, and click on the file there, the same thing happens.
I tried selecting "open with" to open the PDF files Adobe, but then I get a message saying that the .zip is not a supported file type.
Help!!
MacBook Pro, Mac OS X (10.6.8)