It has been speculated that a recent mandatory update to the Xbox 360's dashboard might contain a patch that prevents users from running pirated copies of games.
According to Engadget (opens in new tab), the Microsoft update has silently fixed a hole in the console's software and has blocked players from running burned or copied versions of games like Call of Duty: Black Ops, Modern Warfare 2 and Halo: Reach on the console.
Whilst burned or back-up discs did not work following the update, official copies still worked normally, suggesting that this was an intentional move by Microsoft.
Microsoft claims that the update was designed to re-activate a 'Boot to Disc' feature that was accidentally removed in an earlier software update. The feature allows users to run a game disc as soon as the console is turned on.
It is not yet known whether Microsoft will attempt to install more covert anti-piracy patches disguised as mandatory updates.