[imp] Randomly logged out and blank screens

[Babita]

Hi.

Some of our users are getting booted back to the login screen randomly. 
And sometimes users get a blank screen when they click on a message, ie, 
the sidebar/top menu are visible but the rest is blank. Just wondering if 
anyone else has run into these problems and what you did to resolve them. 
We're running Horde 3.1.4 & IMP 4.1.4 with memcached 1.2.4.

-Babita