Xbox 360 Fanboy has the scoop on the latest backwards compatibility drama for the Xbox 360. In introducing an update to include Tom Clancy titles last week, Microsoft somehow disabled 16:9 support for Halo 2. The update was promptly pulled and patched, but numerous complaints have been posted that the patch does not install correctly, rendering backwards compatibility dead all together. It's unclear how widespread the bug is, but it's a good idea to hold off on the patched update if you haven't already downloaded it.
[via Xbox 360 Fanboy]
UPDATE: According to Microsoft PR, "This error was fixed on Friday afternoon and there are no longer any more problems."

