[plug] mutt is closing my imap mailboxes!

[Benjamin Woods]

Hey guys,

I am using mutt with an imap mailbox.
version 1.4.2i or whatever is included with slackware 10.2.

If i leave my mailbox open and dont touch it for around 3 or 4 minutes, 
next time i go to use it, it says mailbox closed and i have to reopen it.

This is a bit of a pain! (even though its just a matter of c, ! to 
reopen it).

I have set the variable imap_keepalive down, and even tried 5 seconds... 
and it still doesnt work. I also tried compiling mutt 1.5, and that 
still had the problem too!

my isp is iinet, and the imap server is
imap://mail.iinet.net.au

Anyone know how to stop this from happening or what is causing it?