Hey! Thanks for responding. The cgi script runs fine on its own (i.e. no errors or anything, I use strict and warnings, and the output is valid if I echo from stdout to a file and check it out). The error log doesn't show anything. The only thing I can think of is that the script is indeed kind of slow - depending on the user's settings it may take up to a few seconds to process. When I try it out so that it creates small output (a few hundred lines) it usually works fine (also no errors).