Got a problem with a open -e dss 6 lite setup (latest version).

Every few days the machine hangs, it does respond to pings, but no web admin. Also the console is not accessible.

Hardware setup:

Supermicro 16 disk chassis.
Supermicro X8DTN+-F + Intel xeon 5620
Areca 1880 controller
6x 2TB WD Raid Edition disks in RAID 50 configuration

I've checked the logs but apart from some warnings i cannot find the cause of the hang. Which logfiles should i check?