I have had my eris for 16 months. All was well until recently. It will not hold a charge. Got a new battery same problems. I do have task killer. Any ideas on what to do would be greatly appreciated.
Kathy, welcome to the AndroidForums

.
Sorry, I didn't see your post earlier... I have a couple of ideas and questions for you:
1) Are you able to watch the battery charge percentage at all? There are several good apps out in the Market, Circle Battery Widget by Cedric Depoortere is a very useful, simple, and free app that you can use to display the current charge on your screen. Also, Battery Monitor by SIMMO Publications is excellent (I know this dev...he's a member here at AF).
2) Have you tried changing the cables or trying a different charger?
3) You should try to separate whether or not its an app that is draining your battery from the battery being able to be charged. You should be able to do this by trying to charge the phone while the phone is off. If the LED indicator turns green and/or when you do boot-up it shows 100%, then the battery can be charged and you might have an problem with a wake-lock app (i.e., an app that keeps the CPU alive at all times).
4) If the battery won't charge even with the phone turned off, I would be fearful you might have a bad charging port. The Eris's USB / charging port is probably not engineered as solidly as it could have been, since we have also seen a connection between the USB connector and people with trackball issues.
I hope the other guys will chime-in with their ideas, too, since they're bound to have some good ones.
Cheers and good luck!
edit: by the way, I'll probably move this thread over to the Support and Troubleshooting sub-forum sometime tomorrow...I just wanted to let you get more views in the main Eris forum first.