Im pretty casual with my games, so it doesnt bother me too much, but I can see that its annoying.
I too play BC2, and ive teamkilled a few times, on accident. Mostly accidentally switching to rocket rather than repair tool.
I was just playing it, and had a teamkill situation. When I get a new weapon, new scope, or just havent used one in a long time, I fire at a wall to get an idea of how it works. I did it today, and some guy ran past, injuring, but not killing him. He turned round and stared at me for a good 10 seconds before walking off. It was rather nervewracking.
Also, what is HC?