Sessions stopped working with 4.04

Hello all, Of course, apologies if this was covered, I didn't see it in the archives. I recently upgraded to Apache 1.3.19 and PHP 4.04pl1, and my sessions just . . . stopped working. I start the session, register the vars, no errors are generated, but as far as I can tell the actual value is NOT being saved. session_is_registered("myvar") returns a 1, but when $myvar returns nothing, even when I've explicitly set it to a value on the previous page. I set the value, then register the var. PHP writes out a session file, but it only contains the names of the vars I've registered -- shouldn't the values be there as well? This code was all working, now it's busted, any ideas? Might I have missed a compile options? I've been taking blind stabs at workarounds with no luck. Thanks in advance . . . -- Shane