GTS 450: X server crashing randomly (both with flash HW accelaration enabled and disabled)

I’m using 310.19 driver installed from Arch Linux repository on x86_64, no SLI.
My system keep freezing (sometimes I can move mouse but that’s no rule, I can’t switch between terminals using ctrl+alt+[number]) in various situations, ranging from ‘idling’ with only firefox opened, through playing a Q3 engine game (tremulous), to scrolling inside a text editor. I can’t find any connection between these cases. I’ve tried disabling flash HW acceleration but it doesn’t help. Disabling option “RenderAccel” seem to ‘fix’ the issue, though I’ve been testing it only for a day, so it’s not fully confirmed.
Basically, logs say:
[ 1259.259] (WW) NVIDIA(0): WAIT (2, 8, 0x8000, 0x0000d454, 0x0000d1bc)
(EE) [mi] EQ overflowing. Additional events will be discarded until existing events are processed.