Aaaaarrrggghhhhh
Who ever though that putting the default key for "exit without saving folder" next to the key for "change folder" in mutt was a good idea deserves to discover how goatse was produced. Personally.
/me goes to disable the exit keybinding
Update:For those interested in fixing it, put the following in your ~/.muttrc.
bind pager x noop bind index x noop