Naturally, this is pretty bad as Mass Effect 2 is a sprawling 30-hour RPG epic. Bioware says it's aware of the problem and hopes to have a patch submitted to Sony as soon as possible. Until then, the developer reckons restarting the game every few hours should help you to avoid the nasty bug.
And is the co-op local or online?
V for victory
Wallets at the ready
It takes two
Search your feelings, you know it to be true