Same here, with opensuse 10.2 x86_64, on ASUS A8Js, Go 7700, fresh install + beryl-snapshot. On high load i get NVRM: Xid lines in the dmesg buffer and black flickers. Occasionally the X server would hang, and can be killed via ssh and restarted.
NVRM: Xid (0001:00): 6, PE0000 14f8 ffffffff 0000f848 00f8f8f3 00000001
NVRM: Xid (0001:00): 30, L1 -> L0
NVRM: Xid (0001:00): 1, Channel 00000000 Method 00000060 Data 0101020c
I didn't experience hard crashes of the kernel, but sometimes the ipw module (that according to /proc/interrupts is sharing the irq with nvidia) starts showing a weird behaviour (disconnecting from network, logging strange errors) at the same time the display starts flashing black, and recovers when i shut down X.
I can reproduce it, though not so reliabily it takes minutes of trying, loading a large, flash/small text filled page in firefox and scrolling it fast with either the mouse wheel or dragging the bar. It seems related to high load, fast screen updates. Not sure about high network traffic.
I have a second machine (not laptop) with more modest 6150 and exactly the same (software) configuration that is totally stable.
Too bad I tried on that machine, was perfectly satisfied with it and went buying a laptop with a more powerful gpu.