disc read issues

Hello So I was playing Halo 3 with my friends and I get a Disc Unreadable message.

I look on Xbox support (The disc is clean) and it says that I should remove the hardrive and re-insert it.. I alos tried putting to disc in my friends xbox worked fine.. but in mine I get.: This is not an xbox 360 game message.

its starts to read the disc and then says open tray.

or it says play DVD when an xbox 360 is inside.. Anyone help please.

if i was you i will wipe it with a piece of cloth and it should work