I have the following lines in my .emacs.el to swap C-j and C-x:
(keyboard-translate ?\C-x ?\C-j)
(keyboard-translate ?\C-j ?\C-x)
This works fine a vast majority of the time. However, occasionally when I swap back to Emacs from another program, if my first input to Emacs is C-j, it still registers as C-j, instead C-x.
I can do a C-_ to undo, and C-j again, and it's back to C-x. I've only noticed this occasionally with Emacs 23.2.1 and Jan 2011 build of CVS Emacs on Windows Vista. It does repro even with emacs -Q, although usually I have my .emacs.el loaded. I'll update this bug as I get more consistent repro.
--
Le