1up reports that Borderlands players are encountering a rather serious bug that resets their character's skills to zero when they try the game online.
According to posts on the Borderlands forum, skill points and weapon proficiencies are sometimes lost when you join or leave an online play session, and players have no option but to start from scratch with a new character. The problem has been experienced across 360 and PS3.
"We're working on it. Unfortunately there isn't a fix just yet, but when one is available we hope to be able to repair as much of your character data as possible," a Gearbox rep replied to one unlucky player.
Gearbox says the frequency of the bug is "very low" in its known issues list, but it's serious enough that we thought it worth bringing to your attention. You might want to think twice before going online with the game if you don't want to lose progress.