Dieter Maurer wrote:

If you use a Python installation which is not thread enabled, your DCOracle will not release the Python interpreter lock. Your Zope will block while database operations are being executed.

Thanks, Dieter, but it looks like this wasn't it. I'm afraid we just had a funky system installation there. We installed the same software on a new computer and so far (knock on wood) it seems to be working allright. To be sure, I did check, and thread support was compiled into all relevant Pythons. But it was a nice lead. I must say, I don't think I've thanked you properly, but in the last few weeks you have been a great source of knowledge and experience for me. I consider myself very lucky to have you on this list. Thanks, Shai.