I'm pretty certain it's just the legit customers overloading the servers. I'm starting to doubt this DRM will be crackable though. It appears the game asks the server for certain information as to what to do in order to continue. If the game doesn't receive that information, the player is stuck at whatever spot they're in, since the game doesn't have the script to know what to do next. Kind of innovative, but it's really bad for business to fuck over your paying customers.
And what happens when Ubi goes out of business? "Oh, sorry guys. We're shutting the servers down so you may as well throw all your games away.
Thanks for the cash though. Bye! :D"