I experienced a game freeze every time I picked up the schematic for the EMP grenade. There is a menu that comes up in the GUI and tells you how to use it. My guess is that the console couldnt locate the data for this GUI on the HD, and then had a massive psychological breakdown.

So if this happens to you, just go to uninstall whatever disk you are on, then go back without re-installing and play through the part that was weird. Then, optionally, re-install.

(Obviously, you have to use your previous save, as always with bugs in rage.)