I'm using a RPi Model B as a file server back home. I set it up according to HTG's RPi file server guide, so I'm using SFTP to access the files on it. The RPi is wired to a Linksys router functioning as a hub, which is wired to an Airport Extreme. The Airport Extreme gives the RPi a static IP on the local network, and forwards port 22 to it. I use a free No-IP hostname to access it when I'm not at home. The files are stored on a 160GB HDD, which is inside of a powered enclosure.
Every once in a while, the RPi will stop responding to any attempt to connect to it. I.e., when I try to SSH into it, I receive a "Server is unreachable" error. After powering off and powering back on, it runs fine for a week or two, then dies again. At first, I thought it was a power issue, since I was using a smaller 1A supply, so I got a bigger 2A supply that claimed to be designed for the Pi. However, it still keeps doing it.
The big problem is that I'm ~4000 miles away from home for the next two months. So far I've just been getting my sister to unplug it and plug it back in, but any other troubleshooting has to be done from here, or I have to write a guide for my sister.