The desk is a Chamsys MQ200. I was watching it quite closely and watching the web server window in catalyst control and it seems to be when it comes across a file not found but not everytime. Also once the webserver locked up. i can't remember the exact message but ... recieved and exiting spring to mind.

I'm going to harras Chris at Chamsys as well but was wondering if there is any tidying up i can do to try and make the thumbnail image access faster? I've already removed any random non image files that had snuck in to libary folders and removed all redundant librarys