hmm, i've seen this before on a solaris box. iirc, i was just missing some shared compression libs. can you tell us a little more about your environment, specifically your os/distro, so that we can tell you which package(s) to install? you might already have libz.so on your box (find / -name libz.* -print or just use locate if you have findutils around). if you DO have libz.so, just try pointing your LD_LIBRARY_PATH environment variable at it and relinking.

cheers.