Apache - multiple virtual servers but one constantly locks up

[Plight]

Hi there. I am having a bit of a problem with apache.

I am running 3 websites from my server: GLPI (Helpdesk), OCS Reports, and Centreon. GLPI is configured with AutheNTLM to use NTLM pass through authentication (whether this is relevant or not I do not know...).

The problem is, GLPI will stop responding in the middle of the day. Its not consistent so it happens at random times (usually once a day). Looking at the cpu/memory I can not really see anything that is out of the ordinary. If i restart the apache service, it begins working again until once again it refuses to load.

Can someone please tell me where I should begin to troubleshoot this issue? I would think its an overall apache problem but why would my other sites work fine?

[davidanand]

Hi,

check the apache error logs while the program stops responding ..
that will give you a clue why the program is not responding .