I think I might get that occasionally too. Dunno why. Always happens at startup at random times. Does it go into mouse look when you click in the 3D view instead of selecting as well? I usually just wipe my hand across the keyboard hitting all the keys to fix it, guessing its some function I know nothing about toggled by a keystroke. I discovered it in frustration of course, yet it seems to work like a charm. :sneaky2:
Of course, then I usually have to go thru and set the things I do know about back to the way I want.