Zip Archives won't unarchive...

Hi Folks,

I'm in dire straits here. A couple of months ago I decided to compress some of my backups to conserve space on my external drive. I'm running OSX 10.7 and arching the folders didn't seem to be an issue at all. The OSX version of the zip archiver didn't throw any warnings or messages when these archives were created.

When I went back to try and unarchive them using the same utility it wouldn't work. Now, it throws an error to the effect:

Unable to expand "Archive.zip" in "Folder".

(Error 1 - Operation not permitted)

I've tried a number of solutions including the archive into another directory, playing with the permissions, running the zip utility in both 32- and 64-bit modes. I've even moved some of the archives to different versions of OSX and Windows and nothing seems to be working.

Can anyone shed light on this issue?

Thanks

Stefan