Hello again, I have a little bit more information about our specific "crash" environment. First of all, I looked in the Big M Log at the time of the crashes, but couldn't find anything interesting : 8 of the 10 times it was a dtml document containing plain stylesheet data :( I don't think there's any usefull information in here, because the crashes are threading related. Second of all I managed to get a traceback (?) of a gdb session, I don't know if it's any usefull information, I'm not a zope expert on this area, I hope other people (zope developers?) understand what's on the traceback. The customer was not happy with my session, but that environment is the only one that crashes, we still cannot reproduce the error here, nor can we make a testcase for the crash there :( I put the traceback online on http://www.coherence.nl/crash.txt. regards, martijn