Mass Effect 3 users are reporting widespread crashes when trying to load the game, following yesterday's title update.
The issue, which seems to be affecting Xbox 360 versions of the sequel, sees the game lock-up during the boot up sequence, leaving it completely unplayable.
After bombarding the developer with Tweets and forum posts, BioWare responded last night by telling fans it is "aware" of the issue and asking players to describe their problems in order to help create a fix.
For the time being, potential temporary fixes include switching discs and deleting various data in order to access multiplayer.
Some uses have also had success booting up the game while disconnected from Xbox Live.
BioWare said earlier this week that Mass Effect 3's Extended Cut has been designed to offer players more personalised endings that better reflect the choices they made throughout the trilogy.