Pretty much everytime i join a server i am able to play for about 30 seconds then i4mp.dat has stopped working... pops up, It even does it in private match.

Whats the problem?

If i dont give an error, then reinstall the 4D1 version of mw2 and try again.

Scientific Wild-Ass Guess:

That's either the anti-virus closing the application, or something (anti-virus or router firewall) closing the game ports in mid-game.