I have the following issues with my 9500GT card, with driver 177.80 and also the new 177.82:
On startup, the machine often hangs on X start. When this hang occurs, the machine is in a very strange state:
- screen is black, but signal is there - monitor doesn't go into powersave
- machine is unresponsive to keyboard input such as ctrl+alt+backspace or ctrl+alt+F1. However, Caps Lock does toggle the appropriate keyboard LED
- machine responds to ping on the network, but doesn't properly respond to connects (e.g. ssh)
So the only solution is pressing the reset button. On the next boot, it usually works - sometimes not, e.g. occasionally the machine needs three or four reboots until it properly boots into X. But once it has started X alright, it is perfectly stable, and will run for days without problems, even with intensive 3D.
I'm very astonished by the randomness involved (this is the sort of behavior I'd associate with Windows, but have never experienced before - in over 10 years of Linux usage - that after "rebooting several times" something suddenly starts working again
I would say the chance that X starts properly is about 50% per boot.
With the new Beta driver 180.06, the crash doesn't occur on boot (or maybe I was just lucky and haven't experienced it yet, but I did try quite a few times). However, a crash occurs sometimes (again, randomness involved!) on starting compiz (after: "Checking for texture_from_pixmap: present")
Attached is my bug report. Note that the "black screen on boot" occured also with a very simple single screen configuration. Also, I've had the problem on the same machine with another Linux distribution (Debian "lenny" with driver 177.80), so I'm pretty sure it's unrelated to my Ubuntu installation.
All the best, and thanks for the usually-very-good-except-for-these-glitches Linux driver support
Edit: Of course I have read the post "If you have a stability problem, PLEASE read this first"; none of the points mentioned there apply.