Same problem here...Have had it for a while actually. The thing is that it's very random, sometimes I might not get an nv4_disp inifinte loop blue screen for months (playing CSS almost everyday of the week) and then one random day it just happens. As you have said, this also happened to me while playing BF2 (the demo though) and all I did was just stop playing it, I have installed nv4loopfix, rolled back my drivers millions of times I have reinstalled my default drivers that came out with my gpu, doing in it 'accurately' with Driver Cleaner Pro; after a month or so of not having any problems it crashed again tonight while playing CSS. I'm starting to think is my mobos driver problem, it's a pain in the *** trying to update drivers with ABit, so I have no idea what to do.
I know this is no help but I just wanted to share that I have the same problems...
Intel Q6600 G0 @ 3.0 GHz (1.28 V)
G.Skill 4 x 1GB DDR2 (4-4-3-5)
EVGA nVidia 9600GT @700MHz 512MB
WD 250GB SATA
Rosewill RP550 550W