As HawkOwl said, it may be a normal response to colder temperatures. I've seen screens on electronic devices that were blank or only partially functional when they were cold (for example, a mobile radio in my vehicle when it was below zero F overnight). Or perhaps you have a battery that is marginal and unable to provide the display with the proper voltage as the temperature drops.

The solution, of course, is to dial it up to 400 watts and warm the computer with your radiant energy.