After months of frustration I have finally solved the "no mappable mouse buttons" bug that can be found in the Lithtech engine.

To me it seems to only affect certain system configurations (most likely Logitech G15 or MX revolution software).

I currently only seen the bug in Shogo: Mobile Armor Division (Lithtech 1.0) and Alien Vs. Predator 2 (Lithtech Talon).
The only way to fix it (at the moment) is to manually bind the mouse buttons.

you can read about the Lithtech engine on wiki
http://en.wikipedia.org/wiki/Lithtech