Ok...just updated mine to JPO...not!....stuck on the s logo and vibrating every minute or so. Just got off the phone to o2 and its a known problem to them and they are doing a doorstep swap on monday.
Mine has done that a few times when trying different roms i just boot into recovery and clear and reset and it goes.
if anyone after the stock MSN email look i used this its taken from the Galaxy tab but works fine on this.
http://forum.xda-developers.com/showthread.php?t=810454