It has now happened 2 times in the last 2 days when I start a full new backup from a Mac OsX Lion laptop using Time Machine over a wifi network. I got a message on the laptop that it needed to perform a full backup, rather than incremental and somewhere during the process the Synology shutdown completely.
Last night I noticed the synology 410 unit was totally dark and off... so I tried to restart using the power button. Nothing but a quick blink of a light and silence. So after unplugging it for a few minutes and then restoring power, I was able to hit the power button and bring it up. No messages in any log files that I found and everything acted normal.
I left it running and the laptop tried to do a backup again... this morning, the synology is dark and shutdown again!