Computer unstable at lower temperatures

I almost wonder if you have a bad solder joint somewhere on your computer. As I'm sure you know, metal contracts when cold, and expands when it warms. I'm wondering if there is a bad solder joint that is pulling away from the motherboard, causing an intermittent connection when cold, but as it warms up, the joint is pressed against the board, creating a stable connection.

Unfortunately, even someone with experience could have difficulty finding the possibly single point on something as large as a motherboard.

If you're wanting to take a look yourself, this guide will give you some idea of what you're looking for.