Grab tool in mouselook

[Vit Deos]

Hello there, I have some very bad bug/glitch/whatever. Basically, when I switch to mouselook, and press left mouse button, I lose ability to rotate avatar, instead getting grab tool, like the one which appears when you try to move other persone physical object. Because of this thing I can't really shoot any gun. Tried some relogging, cache clearing, no result for now. Any help please?