I bought a SP2 last week and have the same problem described in this thread.
If you bought it new, exchange it for another unit where you bought it.
I actually just received my replacement unit after a nearly two month fiasco. It is in "okay" condition - a couple of scuff marks on the back and the area around the battery connector is scratched and the SN is lower than my current SP2. I'll be checking for this battery problem, but it does not seem widespread.