Last Sunday, all of the sudden my blackberry bold 9000's battery started draining a lot faster than normal... about 15% in half an hour while in standby mode. It's just 8 months old. It's only with an Email/IM plan by provider(AirTel). I don't even use Wi-Fi /internet browsing on it... did no change in overall phone state, except a SIM card replacement with a friend's for a couple of days. Other than that just simple calling and emailing,... surprised why/how it all happened? Tried with cleaning up data, removal/restore memory stick, device resets (alt+right shift+del) but no luck.
While trying suggestions on different blogs/forums online, I found another trick to hit n' try with this, that is physically removing the battery from phone for about a minute (a pure hard reboot). I gave it another shot this way, and luckily it started working normally again. I figured, it was due to some zombie processes running inside device, constantly sucking battery in background. I still have to differentiate why other hard reset (alt+right shift+del) way couldn't kill them? Battery removal is low level reboot.
I thought to share this useful experience with you in case you come across in similar situation. Good luck, Guys.
TIPS TO VARIOUS RESET WAYS
Soft-reset your device
Performing a soft reset stops all applications on the BlackBerry device by pressing the alt+right shift+del keys.
Double-Soft-reset your device
Performing a double-soft reset stops all applications on the BlackBerry device and is nearly the equivalent of a hard reset. Timing however is critical. Perform a soft reset by pressing the alt+right shift+del keys. The screen will go blank. When the screen is no longer black, press the alt+right shift(cap)+del keys again. You should then see another blank screen followed by an hour glass.
Hard-reset your device
The first step in troubleshooting a network, software or hardware error is often to perform a hard reset. With Java® based devices, this is accomplished by removing the battery, while the BlackBerry device is powered on. Hold the battery out for about 30 seconds, and replace. The BlackBerry device will reboot.
Note 1: A hard reset on a C++ based device is accomplished by pressing the Reset button.
Note 2: To perform a hard reset on a RIM models 850, 857, 950, or 957 device, insert the end of a paperclip inside the small hole on the back of the hand held.
You can also refer to this link for knowing more about all type of blackberry resets, I found good for the topic