I've had my Macbook freeze on me the two times I've charged the battery, in sleep mode. I was around the first time, and I could hear the fan spinning (got hot) - then I realized the white LED was not pulsating anymore. Doing a PRAM reset did not help.
I've read about demo Macbooks freezing at the Apple Store, maybe it is the same problem. Has anybody experienced this? If I am one of the few, I'd try to exchange the laptop rather than wait for a firmware fix.
Next time I will try shutting the computer down before charging;