Olimex A20 Crash

[PaceyIV]

I use my Olimex A20 as a sever.
Now, after an uptime of 25 day, the server went down.
I mean that I was unable to connect to it with ssh or to retrieve a webpage with apache: I've got time out error!
The debug console also didn't work: I couldn't interact with it. It print nothing and didn't take my chars.

I press the reset button and reboot the board. 

In the syslog file I can see the last message at 07:45:06: the server completes a munin update request (http://munin-monitoring.org/) and the call to the cron.php of owncloud (http://owncloud.org/).
In the messagge file I can't see nothing usefull.

How can I investigate?
Where can I find something useful?

Thanks
Albano