Several legitimate players of Borderlands 2 on Xbox 360 have experienced the dreaded situation of having their characters thoroughly corrupted, deleted, or made downright unplayable. A warning has appeared on the official forums of Gearbox Studios, with community manager Chris Faylor stating:
Users have begun violating the Xbox Live Code of Conduct by using an external application to maliciously disrupt the experience and sabotage characters of legitimate Borderlands 2 players on Xbox 360.
After extensive internal testing, an update to prevent this disruption has been submitted to Microsoft and will be released as soon as possible. Until then, concerned Xbox 360 players of Borderlands 2 should consider playing online with trusted individuals in non-public sessions. This does not affect players on PC or PlayStation 3.
He also recommends not to play any online games publicly until the patch, already submitted to Microsoft for approval, is made available. Until then, always Save & Quit or select "Continue" if you've been kicked to the main menu. Otherwise, just play it solo or with friends you trust until then.
I'm not trusting my Level 50 Commando with a legitimately farmed Bee Shield with anyone until it's fixed.