Thanks for the help. I am running XP, and I have a GB of ram. I just downloaded the 5.6 Catalysts again, this time without the catalyst control center (we'll see if this makes a difference). It seems like such a horrible lockup that I'd blame the overall stability of my system, except for that it's rock solid in normal use and also in CS:S (the other game I play frequently).
As with almost any computer issue, I'm sure this is resolvable. I just hope it doesn't take hours of looking at message boards and numerous tweaks to get there...
Lastly, I'm considering upgrading to an X800XL or 6800GT which might fix the problem (as a bonus to the performance improvement in general), but at the very least I'd like to wait til the prices settle down due to the impending G70 release; that might mean a month of playing buggy BF2 or *gasp* no BF2 at all!