I was playing halo2 campaign on my 360 and I noticed that some images get burned into the screen. I snapped pictures of the arbiter's silhouette, burned into the left side of the screen. One of those bigger forerunner robots also got burned into the screen.
-
does it look like a white overlay of the thing/map that you are playing? (like Lockout in MP)? If it does, find the nearest cliff and jump off (I'm serious, this happens in Delta Halo, I just do the tank launch glitch thing for fun, and when I spawn back the thing is gone.) There is a death zone ("fatal falling damage") area on almost every campaign level... So try that first.