A client of mine insisted in running Zope on Win2k, so I installed Zope 2.3.4 (some time ago) on their server and also a few products/sites I built for them. The machine has been running now for about 8 months. They don't change much, but it is relatively heavily loaded. They pack the ZODB monthly and backup regularly. On two occasions in the past 8 months, we have noticed very peculiar permissions problems. Several months ago, all of a sudden, several of the users could no longer access the ZMI. Also sections of the site returned permissions errors for no reason. Sometimes specific DTML methods simply refused to display with permissions errors. After many hours of investigating we found no possible logic to this. I then exported the entire ZODB and re-imported it all into a fresh ZODB. All was fine again. Now, several months later the same problem has re-appeared. Again they get weird permissions errors on certain objects, but no real logic or pattern to the errors. Creating new users does not always work. Old users get locked out. Some DTML methods will not work. It looks very much like the ZODB simply gets corrupt over time. I can fix this by exporting-importing again, but I am wondering if anybody else has any experience of a similar problem or solution? Tom