I've got a pretty long-running script. In our live environment this runs under command line PHP, but for convenience on my dev machine I just run it through Apache.
Initially I got an error
Fatal error: Maximum execution time of 30 seconds exceeded
No problem - just up the max_execution_time parameter to zero in my php.ini to give an infinite execution time, restart Apache, and start again. Trouble was, after about ten minutes, I got a slightly different error: