I don't want to be rude, but there's not much information here. Other than the fact you're in the Unix/Linux forum at PHP Builder, we can therefore assume the programming language for the system calls, and one or two possible operating systems. We know nearly nothing about your situation in reality. What else do you know? And if the answer is "nothing else", can you find out?
When you say "the server crashes", do you mean the box itself (OS) or the web server software (should we presume Apache?)
What do the relevant logs say?
What, for that matter, does Google say?