[imp] IMP logs me out after I follow a link

[michael_imp at msi.net.au]

Hi,

Just installed IMP 2.2.6 for Woody Debian (kernel 2.4.23).  The problem I
am having is that I cannot hit *any* of the IMP interface links without it
logging me out of the system and prompting for me to enter my auth details
again.  Functionally, I cannot get beyond the list of unread emails in my
INBOX....

My IMAP logs tell me that I am logging in successfully :

	imapd[23110]: connect from 127.0.0.1
	imapd[23110]: imap service init from 127.0.0.1
	imapd[23110]: Authenticated user=xxx host=localhost [127.0.0.1]
	imapd[23110]: Logout user=xxx host=localhost [127.0.0.1]

And Apache tells me lots of the following immediately after I hit any of
the links (in this case, just trying to view a message) :

"GET /horde/imp/message.php3?index=1&array_index=0 HTTP/1.1" 302 5 "http://xxx.xxx.xxx.xxx/horde/imp/mailbox.php3" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.1) Gecko/20020826"
"GET /horde/imp/select.php3?language=en HTTP/1.1" 200 407 "http://xxx.xxx.xxx.xxx/horde/imp/login.php3?reason=login" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.1) Gecko/20020826"

I can confirm that cookies are enabled in my browser.  Does horde/imp keep
any logging information I can try to diagnose this issue with?

I'd like to stress that it is *any* link I try to follow in the interface
which generates this condition; so it must be a fundamental error in the
way HORDE or IMP have been configured on my system...

Any ideas where I might start to look?

All help very sincerely appreciated.

--
Michael Pearson