[imp] IMP Sessions time out, blank pages

[Jeff Garvas]

I'm running into some weird problems all of a sudden lately.

I can login, read some email, and move between mailbox folders (IMAP), but
at some point the system will randomly break and present a blank page.

Once this happens if you logout and log back in it presents the blank
page and you can't get back without restarting apache.  Once I received
a message that the session had expired (may not be related).

After login I'm redirected to this URL:

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

...and there is no content at all in the browser between body tags.

I am using Ioncube's php accelerator, have not made any changes to the
php.ini file, nor have I made any changes (that I know of) to the way
permissions are being handle.  This installation was reliable for months
and suddenly broke.  I can not tie the breakage to any changes on the
system, so I'm not exactly sure what caused it.

This is imp 3.2.5 and horde 2.2.5.   Anyone know where I should be looking
for a cause? 

-Jeff