Well first off your in Montana. You JUST received standardized FedEx shipping to your STATE two years ago. Packages are still picked up at the post office because knowing which log cabin is yours is next to impossible. LOL! Just kidding ... mostly.
Seriously, i dont doubt your having a problem but i would start with calling your ISP during one of these outages and have them verify they are able to reach your modem. It could be the cold weather is causing problems with your connection, DSL or cable are nothing more then copper and it can still freeze and cause problems.