I've started playing Left 4 Dead after a long time, but it appears that one of the latest updates seem to be giving me the bluescreen error after 5 minute play time. So far this has occured 3 times in a row, and have created this thread just in case anybody else has a similar problem or a solution. I'll try my own solutions too, so I'll report back. It seems that I'm having the problem in singleplayer as well, so its not a network problem. I'll be downloading latest drivers 185.50 today
I doubt this has anything to do with Network Problems. I would check if it ever happens outside of L4D.
BCCode 124 is driver related indeed. It can be caused by many things though, such as ethernet / sound card or graphics card drivers. Made any hardware changes recently? It will be tricky to put your finger on the problem, but if you have a creative sound card it may well be that.