Are you still using the stock battery that came with the camera? That's probably why.....
If you can find this battery (with the leds) for your model, I would seriously consider it.
http://www.compusa.com/products/product_info.asp?product_code=311348&pfp=BROWSE It's great because you can find out right away if it's charged or not!
Just be careful of anything on eBay that starts with "Performance", "Pro", "Titanium ", etc... It's most likely crap!