long running php script won't complete :(

Hi. I've got a piece of code that builds up a multi-meg test array for my opensourced http://mediabeez.ws/products/htmlMicroscope var_dump() improvement, and when I run it for longer than about 20 minutes, the browser just calls it quits.. :( Firefox, and chrome. I'd like to do this with a browser call, if all else fails I suppose I can run the generation of the test array from the commandline, but I prefer calling from the browser.. So, I'm doing ob_start(), then start the main loop which does echo '.'; ob_flush(); flush();. I've got my KeepAliveTime set to 25 seconds, as per http://www.pctools.com/guides/registry/detail/891/ And I'm calling this from my browser to the domain name that points back to the machine I run the browser on, latest wampserver on windows 7. Calling via localhost doesn't work somehow. Is there anything obvious I've missed?