Paul Reinheimer came across a small bug in a recent PHP 5.2.x release of the language - a debugging message left in by mistake.

If you get an error when PHP launches along the lines of: "PHP Warning: PHP Startup: mm_create(0, /var/www/phpSessionStorage/session_mm_cli1000) failed, err mm:core: failed to open semaphore file (Permission denied) in Unknown on line 0" you're going to either need to upgrade to PHP 5.3.0 or wait for PHP 5.2.12.

It seems that some debugging code made it into the core code (but it's been corrected in the branches).