Does the game have any sort of install or cache? A system file even a few MBs large?
I can't remember if it does, but occasionally that system file will get bugged, which will cause problems for a game that no one else seems to experience. If there is such a file, I'd suggest deleting it. It'll recreate it next time you play the game, and hopefully all will be fixed.
However, I don't remember their being an install for GoWIII, but for all I know it was just so small I didn't notice it. Like how Uncharted/Killzone have a tiny, <100MB system file they create on the HDD.