Having just bought a D7000 I now read a lot of comments about it constantly overexposing. Is this a fact? or it's not being used properly. Please bear in mind that I am a relative newby to digital SLR's.
I never had any issues. Assuming this is a used camera, I suggest you reset it and work from there. You don't want some obscure setting from the previous owner coming back to haunt you. Do the 2 button reset. That does not do everything so also reset the shooting menu and the custom menu.