Well, I figured just as much. And when I have other devices on the back USB ports, the voltage is even lower than one on the front, I'm assuming.

And usually the N900 is already running, but sometimes the battery only lasts a few hours on "normal use" and then, before I notice it's 5%, it's flat.

I'm just saying that there should be a way to only have the device such that USB Flashing mode ready when I press a button, but otherwise, do nothing while it's charging. What Android does is it has its own bootloader load up when you power on and hold a couple hardware buttons, and then it allows reflashing from there. If only the N900 did it this way...

And the random reboots I have with Maemo and NITDroid don't help either. May be due to overheating.