EA DICE has announced that the Xbox 360 version of Battlefield: Bad Company 2 will be seeing some extensive maintenance tomorrow for quite a few hours. A similar thing just occurred on the PlayStation 3 version of the game.
The post suggests that players might see some minor stat discrepancies around when the downtime will take place, but this should diminish shortly after the game goes back up.
Downtime will take place at the following time (please note this is the same time, just different time zones):
23:00 PM PST Monday "“ 06:00 AM PST
07:00 AM GMT Tuesday "“ 14:00 GMT AM
08:00 AM CET Tuesday "“ 15:00 PM CET