memory allocation error

Hi all, I've been chasing around a memory allocation error for some time and can't figure it out. It is somewhat random - I can run the script 3 times and then it will happen, or sometimes the first time. It happens at the very end of a script, actually after the script has finished running. I will see the following after the closing </html> tag: Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 494142432 bytes) in Unknown on line 0 Just previous to this my mem usage is 3772104 The script itself does some database work (deletes, inserts, selects) but nothing very heavy and writes out an XML file. I use adodb 5.18, the server is PHP 5.3.18 (this was updated recently) and it is a VPS on inmotionhosting.com. As you can see, the memory limit is 256M so it's really high and I never see that I'm using more than 4M. The error doesn't fall through my error class - I'm assuming that's because it is happening after the script is complete. I am completely out of ideas on how to trap it or figure it out. Any ideas would be appreciated!