[horde] Session issues?

[Kevin Konowalec]

memcached-1.2.4
horde 3.2.1
Imp 4.2
PHP 5.2.3


Has anyone noticed any session issues running the latest Horde/imp  
with memcached?  We're starting to get complaints of users getting  
kicked off randomly and inexplicably.  They could be composing a  
message and on sending get kicked back to the login screen in the  
compose window itself.  Others have complained of just leaving the  
inbox open and after a while they'll find themselves at the front  
door.  In the past these have all been attributed to session  
problems.  We don't have any sort

We currently have 4 memcached servers running a total of about 6GB of  
memory space for sessions.  These servers are rebooted nightly to make  
sure any cruft is cleaned out.  But yet the problems persist.  We're  
not getting a flood of these kinds of calls yet but with classes  
starting next week I expect a flood of calls about this problem and in  
the past users being kicked off - especially having just composed a  
war-and-peace sized email only to have it evaporate - tends to send  
people a little squirrelly.  So any suggestions would be helpful.

I've hard-linked one of our users to a test instance with full  
debugging turned on to see if we can trap this happening again but  
it's one of those needle in a haystack sort of things.  It may pan out  
or it may not...

Thanks

K