A recent Fallout: New Vegas patch made the game almost unplayable for most Xbox 360 owners by causing problems with save games. The problem was so bad that Bethesda urged the 360-owning members of the community to decline the update when it was offered.
An updated entry on the Bethesda forums indicates that as of April 30, the problems have been resolved, and the update should be available for all platforms. The Xbox 360-specific issues have been fixed for English language versions of the game, with other territories to follow shortly. The patch itself includes a number of balance tweaks, which producer Jason Bergman outlines in this post.
Fallout: New Vegas has been riddled with bugs since its release.