I'm having the same problem on the German Wikipedia. Maybe this info helps a bit to figure out what's going on.
I cleared all the APC cache files, and I no longer see the error on the English or German wikis.
I also installed your patch and upgraded to PHP 4.2.3. The process may not have gone as smoothly as I had hoped, but it seems to be up now.
wikipedia-l@lists.wikimedia.org