Slow sessions.

I have a load balanced website with 5 web servers. Currently, they run php 5.1.4 (for pdflib reasons). I'm going to upgrade them, so I removed one from the load balancer and installed php 5.2.17 on it. I originally installed 5.3, but some of the code was causing problems, so I went back to the latest version of 5.2. The problem I'm having is that the session_start() call consistently takes about 30 seconds to run. If I create a file that just has a session_start call in it and nothing else, it takes about thirty seconds. I've tried a bunch of different things, and can't figure out what the problem is. I've created a file that grabs the session cookie, opens the session file (fopen), reads it, writes to it, and closes it, and that file runs in less than 1/10 of a second. It doesn't seem to be a file locking issue. I've searched for a solution, and so far I haven't found one. The common work-around is to write a user session management system, which I would do if I could, but with the load balanced environment, I kind of need to keep the current system in place. Any suggestions would be appreciated. I've run out of my own options to try. Thanks. -- Rob