Windows 7: System Freeze while playing BF 3 Multiplayer.

hello, whenever i play BF 3 online, after a few minutes my system freezes, but no blue screen appears. This problem does not occur when i play single player. I used to have the same problem earlier, but then it happened even while playing offline. i got my motherboard replaced. Now it will only happen while playing online, BUT without a blue screen.
also, i tried to find dump file but it is not there, even the software that u suggested using "bluescreenview" is not showing any crash. although i have attached the other files.
what should i do

thanks.

please can anyone help me with this, or evn how can i get minidump files to show up! i have enabled the small dump file option in startup and recovery and i m the administrator, but still it wont generate any dump file.

Recently my system has started acting strange, and while playing bf 3 online, it would just freeze. it wont give a Bsod, but just freeze. and when i looked in my windows there is no minidump folder (and i have changed option to small minidump and am an adiminstrator). Now i posted this in crash and debugging, but no one seems to pay attention. since i dont have dump files. So Please, can anyone tell me what am i supposed to do? how can i get dump files? and are they only generated when u get a blue screen and not on system crash?

thanks