Gnus has trouble reconnecting to an IMAP server?

[Gregory Novak]

I use Gnus to read mail with the nnimap backend.  I'm using Gnus
version 5.11 and Emacs 21.4 and a version from CVS.  

Sometimes, if the connection to the imap server has been idle for too
long, Gnus disconnects.  It then seems to have a hard time
reconnecting.  If I hit 'g' in the *Group* buffer, after an
inordinately long time (minutes) it will finally fail with an error,
after which another 'g' reconnects without trouble.  However, if I
interrupt this process, Gnus is left in some kind of intermediate
state where it can't talk to the imap server.  It is sometimes
necessary to kill all the Gnus buffers and restart Gnus (sometimes,
even to do this twice when the restarted Gnus fails to successfully
negotiate an Imap connection).  

I have several related questions:
1) Is it possible to have Gnus send trivial chatter to the Imap server
every few minutes to keep the connection live?  I've set up gnus-demon
to check for new mail every 10 minutes, but I must have it do this
synchronously because Emacs is seldom idle for a full minute.
2) Is it possible to have the nnimap backend be more pessimistic about
the connection?  Ie, if it doens't get a response in ~10 seconds, tear
down the connection and make a new one.

Some info about my connection which may be relevant... the server is
Courier and the info it sends upon connection is: 

  * OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE
    THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA AUTH=CRAM-MD5
    AUTH=CRAM-SHA1 AUTH=PLAIN IDLE ACL ACL2=UNION STARTTLS]
    Courier-IMAP ready. Copyright 1998-2005 Double Precision, Inc.
    See COPYING for distribution information. 

The info displayed in the message line indicates that it's using
STARTTLS to authenticate.

Thanks for any guidance,
Greg