About a month ago I was using my EVO with about 80% on it and out of no ware it just shut down. When I turned it back on it had 1% of battery left. I don't know why this happened with a good amount of battery left. It does this at least twice a day. And I barely use it when it does this. When it turns off it doesn't even say "shutting down" like it usually does. It just completely shuts off without notice. Is it a battery problem or what? HELP!!!!! This is really frustrating. 
THANKS!

THANKS!