Long pages cropped accessing mSQL database

Hi, I'm using PHP 4.0.3pl1 to access a list of users and their details, stored in an mSQL database to then output in a table. This list is about 230 users long, but will potentially grow to in excess of 1000, and there are three fields that I'm retrieving from it. However, when it is sent to the browser, it randomly cuts short the list at varying points and displays nothing after that point. It's like the script has got to that place and given up. The script is well within the 30 second execute time (almost instantaneous) and I can't really see that it consumes more than 8MB (plus I assume if it did it would break at the same place every time). Does anyone know what this could be a symptom of and how to fix it? Thanks, Louis