Troubleshooting a embedded arm system hanging

I have a pink pogoplug v2 that I have debian installed on it acting as my personal email server. it is a 1.2ghz arm processor with 256mb ddr2 memory and a 250gb usb hard drive for root filesystem.

My problem is that it seems to stop working after about a week. It's lights are still on but I cannot access it over the network. Access to it is through network, USB ports and an internal serial console. I havent seen anything printed to the serial console that looks like an error.

I was worried it was getting too hot so i moved it from my warm shed to my air conditioned room but the same problem occurs after about a week.

Can anyone recommend a place to start when trying to troubleshoot a problem like this?

Greetingz!

I had a similar issue with a Seagate DockStar (almost the exact same device). Basically I setup the following cron jobs;

1 * * * * uptime >> ~/check_uptime.log
1 * * * * ping -c 1 google.com 2>&1 >> ~/check_ping.log
1 * * * * printf "===\n===\n===\n >> ~/check_procs.log ; /usr/bin/ps -ef >> ~/check_procs.log
1 * * * * printf "===\n===\n===\n >> ~/check_dmesg.log ; dmesg >> ~/check_dmesg.log

If I remember correctly, there was an NTP daemon that was throwing a fit and locking up the lil guy.

Thanks! I'll give that a try and see what shows up.
This device does not have a hardware clock so ntp is kinda necessary.