Disable / Modify Shortcut keys in Firefox

I had a problem with Ctrl-Shift-P (start private browsing) interfering with the Ctrl-Shift-P on dotSUB for starting/stopping video play.

Seems dumb, but I can't edit it within firefox config, I had to load a keyconfig extension.
Restart the browser, go to Tools/Keyconfig, then scroll down to the shortcut key, and disable.

keyconfig allows you to change keyboard shortcuts. [Firefox, Thunderbird, Sunbird, Flock, ChatZilla on XULRunner, and Toolkit 1.9 Applications (Prism, Songbird, McCoy, the upcoming SeaMonkey 2.0, ...)]

http://forums.mozillazine.org/viewtopic.php?t=72994