My New Vegas game was freezeing up constantly every time I tried to leave Goodsprings after completing the last quest there. In a last ditch effort to try and get the game working again, I did the following:

Step 1: Deleted ALL of my New Vegas game content from my Xbox

Step 2: Cleared the cache files.

Step 3: Re-installed New Vegas

Step 4: DID NOT re-download my Gamestop DLC equipment package.

After doing all of this, my New Vegas game works fine. I believe that the DLC packages from the pre-orders may be the problem. If you are having problems with freezeups, try doing what I did, let me know if it works for anyone else.