I agree that it's probably the battery. I have a solar charger, and during our recent cold snap (highs in single digits for a week), didn't get any pictures. My camera (Moultrie 2.1) status was showing data/time, which usually indicates the battery has gone dead or been disconnected. I have a solar panel charger, but didn't think to look at the actual battery status. When I brought it back to the house to re-charge on the wall charger, it was fully charged. My guess is that the cold did not allow the battery to function, causing the camera to reset. Then when it warmed up, it charged the battery back up. Since it had been reset, it couldn't take any pictures because it was in setup mode.

I also believe my infrared sensor has problems in the rain. I've never gotten a single picture in the rain.