Tin Quits when reading a message

First, apologies if this is a duplicate. I posted this via Google
groups yesterday but I'm not sure if that gets forwarded to this list
or not.

I've just upgraded to Mac OS X 10.4 ("Tiger") and started using tin
again after having not used it for a while. However I've found that
whenever I try to read a message it quits out of tin. This happens
whether I use space to read the next unread, or press enter or
right-arrow when the message is highlighted.

This is the case with the Darwin Ports version 1.6.2 and 1.7.8 which I
built from sources on tin.org.

I used to use tin some time ago (on 10.3) and I don't remember having
this problem. However it's possible that it's a configuration thing
that I changed and forgot about.

Anyone any thoughts on what might cause this? 

Thanks
-- 
Paul Mason