Battery Drain of my Android 2.1 Phone

The other night I went to bed as usual and put my phone on silent mode and left it by my night stand.  Usually in the morning I just switch it back to normal mode and the battery level is only slightly lower than when I went to bed.  Not much battery drain when the phone is not in use other than stand by mode.  This particular morning I got up and the phone was dead.  I plugged it in and was able to turn it on only to find the batter was completely drained!  This was a bit disturbing.  Especially since I use task killer and never leave background tasks running. I continued to experiment during the day with charging to see what was going on.  I couldn't get it to charge more than 1/3 the way.  So, I went to the Verizon store at lunch and asked them about it.  Their response was, "Oh, with those phones you have to take out the battery, wait a moment then re-insert the battery to "re-register" the battery with the phone."  While this sounded like bogus hokus pokus, I decided to give it a try.  The after noon went much the same.  The phone still would not charge.  After work I went back and they decided to give me a new battery.  Well that didn't seem to make much difference.  So, I searched for similar issues and found nothing that really matched this problem.  Finally I decided it was a software "glitch" and recorded all the apps I had installed and my screen layouts then went for the "Hard reset" option.  This resets the phone to the factory settings.  Then I had to reactivate the phone but that was automated OTA (over the air).  So I was able to re-download my apps and put back all my screen icons.  Once I logged back in to Google all my contacts, email, calendar, etc. came right back.  This step of Settings, Privacy, Factory data reset fixed my problem. By the way, HTC's site says the Factory data reset is under Settings, Security.  I'm sure this refers to Android 1.5 that was originally on the phone.