Cold and no issues. But in all seriousness, search, because this topic has been beaten to death. Personally, I would start off by pointing the finger to the Opus. It has a couple of under voltage issues in cold weather.
Your hard drive won't spin up when it is to cold. Only way to fix is some Compact flash to IDE adapters and running a compact flash card so you can run the hard drive as an external unit that you take in with you.