Infinite loops with PHP

Hi all I'm working for an ISP which wants to give the user the possibility to write PHP scripts. Now I'm worried about the situation, where a user writes a script which lets the interpreter run in an infinite loop, which would degrade server performance until the server is restarted. Is there some timeout value, which automatically lets the PHP interpreter stop after some time? Is it configurable? If there is no timeout feature, how can this problem be solved? Please reply to the email address Thanks for your time bye -- Sam Jordan