Originally Posted by
ElcyionLacar
It's just kinda pointless to expect this to work. Even on the odd chance that it is working (tho' I think the WoW database would have limits placed on the maximum value of a characters xp at this time), the database isn't extended into the 71 range yet.
There's going to be a substantial down time at one point as they upgrade all of the servers to be lich king compliant at some stage in the future, and that is when the new xp tables will be added.
Frankly, if you don't own BC you can't hit 61 (or gain xp towards it), so there's no reason for a character to be able to hit 71(or gain xp at 70) without wotlk.
As the previous posters pointed out, this is simply a gui bug. It's possible that when wotlk comes out (and you buy it) you'll be able to gain xp from it again.