I use Ubuntu 6.06.2 LTS with Server version: Apache/2.0.55; built:Aug 16 2010 18:25:39 and PHP 5.1.2 (cli) (built: Sep 16 2010 20:32:18). All my 4 Cores are constantly at 100% and the system begins to accumulate load. A restart for apache fixes the problem temporarily. I made a strace to the pid of the apache processes that keep the CPU busy. I get the following message continuously: gettimeofday({1285234145, 989639}, NULL) = 0 Do you have any ideas where this problem comes from? Thank you. UPDATE: The problem came from an application error that generated an infinite loop. Thank you all for your great help.