Well, it's a new phenomenon for me, as it only started after the Holiday update. So, I don't have a lot of data points to consider. As noted earlier, I thought it might possibly be correlated with my USB stick, but now I'm not so sure.
I basically have 6 data points:
1) Christmas Eve, went skiing, drove 80mi, 1h45m; after 1h got the error. No preconditioning, so in that hr, could the cabin have warmed up enough to trigger the error?
2) NY Eve, went skiing, drove 80m, 1h35m; preconditioned, and when I got in the car, the camera was unavailable.
3) Day after NY, went skiing, drove 80m, 1h45m; did not precondition, did not heat the cabin, and made it the whole way there and back, with no errors.
So, essentially I have 6 data points for 3 trips, there and back. On Trip 2, I pre-heated the cabin, and the camera didn't work. On Trip 3, I left the cabin cold, and the camera worked. On Trip 1, I didn't pre-heat the cabin, but turned on the heat while driving, and the error occurred about 1hr into my drive.
I'm going skiing tomorrow! I'll keep the heat off again, to see if I can avoid the error. Today, on my short 10mi trip into town, I'll see if I can trigger the error by pre-conditioning.