I've noticed this too. I had it happening consistently in a lobby on Swiftwater the other night, but I HAVE had it happen in other maps too, though it's much rarer.
I launch with
-novid -nod3d9ex -window -noborder
but I don't use a graphics config, just settings I manually enter.
Here's my config.cfg if it'll help.
Also, Sigafoo had this happening to him on stream on pro_viaduct and Gullywash. He didn't crash, though.