I have been hearing a lot about Mass Effect 3 having a lot of problems. It seems that it is a hit and miss problem. Some systems it works just fine and others not good. Anyway I still need to ask a few questions.
Does this happen when you just turned on your PC and launched the game or has your system been on for a while and then when you launch the game? Is this game Steam related? I don't know that, I don't play the game.
All your drivers and I mean all drivers, Sound, bios, etc up to date? Have you tried running the game with your antivirus off? Have you checked your eventviewer to see what the trouble is?
What is your system spec's? For now get back to all of us with the answers so we can trim down the stuff that is not causing your problem. Good luck.