Load your desired save file (I believe you may need to load one from outside the casino or other place that confiscate your weapons).A guide window will immediately open once the game launches and will ask if you want to apply the available update for the game. Launch Fallout New Vegas as you normally would.Find the file labeled 'Fallout New Vegas Title Update #5 (the number on yours could be higher if you are reading this after another update, or lower if you somehow have an old update) and DELETE it (do NOT move it, as the game will still detect it).Find 'Fallout: New Vegas' and select it.
(NOTE: If you rely on your auto-save or your auto-save is your most recent save you would like to play from, I recommend saving a new manual file before attempting the steps below.) The solution for me ended up being very simple but I will list step by step directions to clear any confusion.
The poster who made the comment about the patch deletion only working on the PC was wrong, fortunately for those of us on the XBox 360 (and hopefully for you PS3 users as well).