My Xbox 360 has problems with MWII!!!?

My Xbox 360 is the new minute, black version (though I remember not the model's title). I purchased it last fall (2010) and it has been running pretty smoothly. But suddenly, when I was playing Modern Warfare II, in the middle of online play, an Xbox sign came up informing me that the disk could not be read, that I should check the disk for scratches and/or restart the Xbox 360. Well, I checked the disk and it is as clean as a cut diamond. I restarted the Xbox 360 and tried to the play the game again; about ten or twenty minutes into online play the same thing occurred. This plight has interrupted perfectly fine gameplay three or four times within a few hours of nightly gameplay at random occasions - even once I played for a whole our after the third time it occurred without any problems. Obviously the disk is fine, and the game plays fine! So what is the problem?