[Zope] Zope instance restarting itself

Hello, I have a Zope-2.6.1 instance running which behaves very weird. It restarts itself :-( First I discovered that the Data.fs truncated and restarted Zope. I then used fsrecovery.py on the Data.fs and it removed a bad transaction. Then I started Zope with the new Data.fs file. Now the instans restarts at the same time but without the error - infact withput any error. Any hints on how I can debug this? Greetings, Gitte Wange