Folks, I've tried to find an answer by searching the collector, the mailing list archives, and google. Didn't have much luck. I've got a site running Zope 2.6.1 under RH Linux. We are using a current version of Plone. The whole thing was set up about a month and a half ago, and after discovering that running on Sun was at times problematic, we've had very good results running under RH 9. I've got about a hundred site members and I've had three instances now where for some as yet undetermined reason, something in a user's account becomes corrupted and they can no longer log in. When this happens, each time the user goes to log in, a stack trace is created. Apparently this happens after the user password is compared to what Zope knows, because changing the user password through the management interface will instead cause the expected password failure page to be rendered. Deleting the user and recreating using the same userid doesn't resolve the problem which implies that there is some kind of persistence at work here. If you recreate as the same userid and with a new password, logging in causes the same stack trace to be displayed. I've attached one stack trace, but the other two are identical except for the instance number. I'm new to Zope and finding that my lack of familiarity with the code base is slowing me down. If anyone out there can suggest some troubleshooting approaches, I would appreciate it. When this was limited to just one person it was an annoyance, but now its become critical to site functioning to solve this problem. Thanks in advance, John Charles John Pedersen Sr. Systems Engineer SRI International Menlo Park, CA 94025 650-859-5913