Sirius presets and iDrive issues

[slowlanemcvane]

So last night my wife and I came back from a vacation in Texas that lasted 11 days. I came back to a sagging rear end (air ride, yay), and knew that the battery was probably a bit low. So when my wife started the car, she got the expected low-battery's warnings, and iDrive wouldn't work, the display remained black and wouldn't even progress to the BMW load screen. I had figured that the car probably needed to be reset or something, so I did a bit of digging and found out how to reset the iDrive (press and hold MUTE-DVD-CD EJECT buttons.). IDrive booted up just fine after a few seconds, then seemed to go through a period or gathering GPS data and linking to Sirius. Finally her music came on, and I was able to scroll through iDrive like normal, but I discovered that the radio no longer had the stored presets (or won't switch to them) and won't store any new presets. I can use the other functions of the iDrive just fine, like reading car status and the navigation features, it seems to be isolated to the radio.

Any ideas about what could possibly be causing this? I like BMWs, but it feels like these cars are the touchiest possible machines, and that even the smallest voltage-related issues cause them no end to glitches and a gremlins that seem to happen for no other earthly reason than to cause an unlucky owner to drive/tow their vehicle to a service center. Thanks in advance, folks.