Early shutdown - 10D??

I'm having a problem with my 10d and was wondering if anyone has experienced a similar problem:
I put in a fully charged battery and within 10 minutes the camera shows a low battery warning. It then operates for a while (50 shots) and then shuts off the camera. If I put the battery back in the charger it shows 3/4 or even full.
Maybe a faulty voltage regulator??
It does this with two different batteries.
I'd like some input before I send it off to Canon Canada, because in my past dealings I've received comments like" It's supposed to work that way

Thanks
Mike

Hw old are the batteries themselves.. ?
Are they a name brand or generic?

It seems unlikely that two of them would die simulteanously,. I agree,. but as they age,. they can get to a point where they will "charge" but the overall out put volatage has dropped to a point where the Camera can't live off of the output provided by the now too far out of spec battery.

The batteries are original Canon, one is almost two years old and the other is about one year old. Maybe it's time to give Sterling Tek a call...