Rmail was giving out a backtrace. I had nothing relevant to rmail in my .emacs file. So I was inclined to think that rmail was at fault. I pasted the backtrace on #email@example.com’s paste. Only to discover that rmail was added with a hook that none of the regulars had ever come across.
Looking at its definition, I soon discovered that shebang.el was the file that containing the hook that was creating the problem. Upon removing the hook and disabling the file from being loaded automatically, I got rmail working properly.
So, who had added thee offending file? I was suspecting my sister would have added since she had used Emacs a few times. But turns out that she knows nothing about adding things to load-path. So, I must have put that file in the load-path for whatever reason. heh, gotta watchout for what I put into the load-path from next time on.