[Zope] unexplained shutdown

Hi all I am running Zope 2.4.3 on Redhat 6.2 to serve a solitary website. This has been running for nearly two months now but has been problematic over the last couple of weeks. At that point the Zope server began shutting itself down, firstly only occassionally but now it is happening every night and I must restart Zope every morning. I have looked at the Z2.log file for any indication of what is happening but without any clarification. Has anyone else encountered a similiar problem or could you perhaps suggest what may be going wrong. TIA Tony