Thanks all for the suggestions. Turning the phone on/off didn't clear the problem and neither did charging the phone while off overnight. I tried that last night and turned the phone on this a.m. with 100% charge. In two hours it was down 25%.
I observed full signal strength all morning, so I don't think it's a bad reception issue either.
I like to use my phone as a music player and losing battery power this quickly just can't go on. I usually am able to get a good 6+ hours of continual music play. I can't even begin to imagine how fast the battery would drain if I added music listening at this point (since it's dropping like a rock just sitting there doing nothing but waiting to be used).
I've noticed there is also a memory leak problem (starts out with 10,000-ish and after a few hours of doing nothing is down to 3,000-4,000 ish - so, I'm going to try hard resetting again and remove a suspect program (MyTools...which I've written about recently). Hopefully, that will resolve the issue. I'll post how that goes.
Devices: T-Mobile MDA (Cingular SIM), i-mate SP5m (sitting in a drawer at the moment while I attempt to migrate to PPC permanently), Cingular 3125 (unlocked and in use on T-Mobile), Motorola MPx220 (retired), Motorola MPx200 (retired)
Accessories: Plantronics Explorer 330 & 2G Patriot Micro-SD (use w/MDA), Kingston 2G mini-SD used in SP5m, Plantronics Discovery 640 & 2G San Disk micro-SD (use w/3125), Jabra A210 BT adapter + Motorola HS805 (retired)