More than likely you are running a different version of slsk, which would explain why the two of you don't see each other.

Bill - if you're running the beta, 1.57 TEST or whatever the version is, it doesn't communicate with the "stable/full" version, 1.56c. If you revert back to the old version or just install 1.56whatever to a separate folder on your comp, you'll see Stringer. He's there all the time, shared folders intact.