[imp] Firefox login problem, not cookies?

[Computer Tech]

Hi all,

openSUSE 10.3
Apache 2.2.4
Horde 3.1.4
Imp H3 4.1.4
PHP 5.2.5
(all of the above "out of the box" openSUSE, with online updates applied.)

Neither Firefox (I've verified 2.0.0.14 and have been told the latest 3 as
well) nor Mac IE 5.1.7 successfully log in to imp.  I haven't done a lot of
testing with the Mac but have played around with Firefox and can't get it to
work reliably.  The odd thing is that every now and then, with no changes in
the server setup, it will work. 

The test.php session counter shows the session count incrementing.
There are no errors in horde.log
The firefox error console only says "the use of captureevents() is
deprecated."

I've looked and looked around the net and various lists (including the
archives of this list) and all I've come up with is that a cookie problem
causes it or at least very similar symptoms.  That doesn't seem to be the
cause here as (I think) I've set sessions to use URL instead of (in addition
to?) cookies.

I've tried setting conf.php $conf['session']['use_only_cookies'] = false;

The URLs changed (now include horde=bunchofrandomcharacters) after I set the
use_only_cookies to false but cookies are also being set.

The only way I've gotten Firefox to log in to Imp succuessfully consistently
is to download the IE tab addon. :)  I read of lots of folks using Firefox
successfully so I must be missing something, but I'm not finding it.  Maybe
it's the blood running into my eyes from the gash on my forehead from
banging my head against the wall on this.

Thanks in advance for any pointers.

rj