Possibly related: After upgrading to 1.7.2-1 from 1.5.something last weekend, I noticed that hitting 'c' <tab> sometimes shows the contents of /var/mail instead of the contents of ~/Mail as it used to.
I've since found out that if hitting 'c' and <tab> is the first thing you do after starting mutt, the behaviour is like it used to be: repeated tabs switch between showing the subscribed folders and the total contents of ~/Mail. However, if you hit 'c', <tab>, 'q', <enter> (you didn't see any folders you wanted to change to) and then again hit 'c' and <tab> now you see the contents of /var/mail instead?! I.e. the behaviour changes if you abort the 'c' action, which is very unexpected. Paul