[imp] imp or horde session crashing

[Jeff Garvas]

Hi folks.  I'm having continued problems with imp or horde losing session
status (or maybe its just a bug).  I am using IMAP and jump back and forth
between an IMAP folder and my INBOX.  Randomly and regularly I keep running
into this situation where IMP crashes.  I get redirected to a URL like this:

http://www.blah.com/horde/imp/mailbox.php?mailbox=INBOX&actionID=105

If I logout, close my browser, and login again it goes to the same
location with a blank page (no data).

What could be causing this and how is restarting apache fixing it?

I'm using:

Apache 1.2.36
horde-2.2.5  
imp-3.2.5 

Thanks,

-Jeff