[Zope] aargh. corrupted zope1.10 install.

I've got a Zope 1.10 install that until this morning was working absolutely fine. Suddenly it's developed a rather bad habit - it seems like loading the ODB is failing in some way. It starts up fine, but attempts to access anything fail. Doing a GET / HTTP/1.0 simply returns back <module 'Main'> I've tried moving the Data.bbb aside, and putting in the Data.bbb.in that the installation shipped with, to no avail. As far as I can see, _nothings_ changed in the system (so sayeth find . -mtime). Anyone? Please? Anthony