I was happily working on my Zope server this morning when all of a sudden all instances of one of my custom ZClasses broke (i.e. they were no longer editable through the ZMI). Initially I though it was something that I had done, but nothing I had done recently could have possibly had any effect on this particular ZClass. So then I went back through the transaction log on the off chance that I had done something that might have caused the problem and I found this transaction : "Rebuilt global product registry by Zope 2002-05-03 10:53:21 AM" It's something that Zope did automatically without my involvement and it was exactly the same time that I first saw the problem. Anyway I undid this transaction and all is peachy again. My ZClass is based on few other Products, but all the other Products are still installed and they are all working to the best of my knowledge. Why would rebuilding the Global Product Registry cause all of my ZClass instances to break ? What the heck is the Global Product Registry ? I don't see mention of it in any of the documentation. thanks for any info., Darcy