In 10.5.6, after running parallels compressor on my VM to shrink it, I then quit parallels. I then righ-click the .pvm file in the Finder and choose "Compress ". Instead of compressing the file to a .zip file, I immediately get a dialog box saying "Copy: An error occurred while adding "" to the archive." If, instead, I first duplicate the .pvm file in the finder, then I'm able to compress the copy just fine. I'm wondering if parallels is leaving some files open?
Same problem, success after restart I had the exact same problem. I restarted my MacBook and was able to compress the .pvm virtual machine image into a .zip file in Finder as expected.