RHEL 5.4 hanging for no apparent reasons

[Yaboto]

The server is loaded with Red-Hat Enterprise Linux 5.4 and connected to an FC SAN. In average, it hangs once every week for no apparent reasons. We cannot trace the cause from any particular log or event. We have to physically press the power button to reset it before work resume.

What are the RHEL 5.4 OS logs that could help us trace the cause of the problem ? 

Please advice

Yaboto

[Gerardo_Arceri]

Is this an HP server? Have you checked the Integrated Management Logs (if available), is there any chance you could upgrade the server to a newer release of the OS (latest is 5.9), 5.4 is waaay outdated and could be the source of your problems.