Alt+F4=secret weapon in Halo PC!
While attempting to play through Deja Vu today, I was forced to end the game due to the fact that at the part on the highway right before the first wraith, our checkpoints stopped working. We passed that part numerous times, only to die in the following wraith part. We simply could now pass these two parts without the checkpoint in between. To be clear, the game says the checkpoint unlocks, but when we die, it brings us back to the checkpoint before. Any advice?