System freeze


I am running FreeBSD 8.2 on a arm cpu.
Everything runs (almost) well,but sometimes the system just freezes.No Uart ,No Etherntet (and no ping) impossibel to get into the system(WD is disabled in this system)and it runs for days before this situation occur....
Question is how to debugg this?
Thanks for your help
If it is old enough to run FreeBSD 8.2 I would consider something is going bad with the hardware.
Maybe log board temps and see if it spikes before crash. Heat could be a hint.
Is the machine internet facing? If so investigate the packets to see if somebody is nuking you.
FreeBSD 8.2 is old enough to have some holes I would think.

Are your logs showing nothing?
cat /var/log/messages | more

Here it says that version was EOL in 2012
No the machine is not connected to the public internet.It could be a heat problem.
Question is how to go about when the system freezes , and there is no contact wit it
by any means.Is there a way to save the stack in flash or similar, to be read after rebooting?
Can a JTAG debugger be used? if so which one?
Syslog shows nothing //var/log/messages).