Just a note that I have been experiencing the same problems, though with keyboard lockup as well.
i can ssh into the box, but have to kill X from there to regain control of the machine.
everything works fine with nv drivers as well, but using nvidia as the driver (the latest one) causes the lockup to occur. it seems to be video related, because if i am just in a shell i can work to my hearts content. but the minute i try to open another window or run something else, it tries to render, then locks up....
Je ne sais RIEN!