By default the Insert and Delete keys will rotate the camera left or right the same way that Q and E do.  I use Delete as my push-to-talk button in Ventrilo and have found it very annoying to try and talk to friends only to have my camera start swinging around in circles. 

I figured it was an easy fix and went into the key mapping menu only to see that those camera movement keys are greyed out and cannot be edited.  In fact, looking at the key mapping menu, the camera rotation keys are only labeled Q and E and they do not even list Insert or Delete as having that function.

Is there something I am missing?  Is there a way for me to edit these keys so that Insert and Delete no longer rotate the camera?