Error 500

[Sman]

Hi!
When I try to access to dinamic page which access to a DB data an ERROR 500 appear:

"couldn't create child process: 22: C:/PHP/php.exe "

Do you know what could happend?

I have problems to show resultsets above 150 registers. I don't know why.
I've intalled PHP with Apache and MySQL in a XP professional.

How does PHP create child process? how many could it create?

Thanks for all.