I have the same problem with my GF4 Ti4600 using 3123 driver. With the 4191 driver, it was crashing my Xserver. I tryed the latest driver (4363) and I have the same messages that with 3123.
You should complain to Nvidia about this problem by reporting it to email@example.com
. The more people complain about this problem, higher are the chances that Nvidia fixes the bug once and for all.