ODST Help

Hi everyone. I bought Halo 3: ODST yesterday, and have played a little bit of the campaign and it seems to be doing fine. I have read some people have problems but i haven't. Yet, when i try to put the multiplayer disc in, it comes up with a blurb (same as the one you get when you unlock an achievement or when you recieve a message) saying that it was ''attempting to read the disc'' or something along those lines. What does this mean, and should i exchange my ODST for a new one?