[imp] (Seemingly) random returns to logon screen

[Myke Place]

Hello,

We are using IMP 3.1 and Horde 2.1 and for the most part we are pleased to
report that everything runs smoothly for about 25,000 users. We use IMAP
for the mail retreval method. We do have a small section of users with
problems that I would like some help or suggestions from the IMP/Horde
community in solving.

It seems that some of our users (at most fifty or sixty out of the 25,000,
that I am aware of,) experience problems wherein they login sucessfully
and are presented with their read and unread messages in IMP. The problem
occurs when the user clicks on a message to read it. As soon as they do
so, they are immediatly returned to the logon screen.

I am baffeled because, so far, I haven't found anything tying this 
behavior together in the webserver or PHP logs. I don't see IMP or Horde 
register a logout in any logs either. It appears that they simply login 
again and again, are presented with the messages, and then after clicking 
on one, they are booted off.

What's interesting is that for these users, if they login from another 
machine, it works fine. Often it just starts for them out of the blue, 
working fine one day and then broken the next.

 My questions for all of you are:

1) Has anyone seen this type of behavior before? I searched the IMP/Horde 
mailing lists archived on MARC and Google and I was unable to find any 
indication of this problem occuring nor a possible solution.

2) Could this be a cookie issue? Could somebody perhaps describe what 
effect the cookies that are set have on a users session?

3) If this is a browser issue, are there any known patches that solve this 
problem? Any suggestions on troubleshooting from this angle?

I would be happy to provide log file snippets or temporary logins for 
anyone who would be willing to take a crack at this. I'm pretty much 
baffeled at this point, I will indeed appreciate some clarity. TIA.

--
Myke Place
mp@xmission.com
www.radiojournal.org