Methinks you missed something. Moving file's around easily breaks a web app.
Originally Posted by CardinalQuest
Check your apache and PHP error logs. I'd suspect that one of them will indicate that an include or other file scan failed since a path could not be found. Enable your error reporting as well on the script in question to test it out:
If something like say a database connection or configuration file fails to load, and you fail to establish said connection, then writing to the database will fail.