Pi stops responding?

My Pi (or maybe its Myserver6) has crashed twice today,  I keep it updated regularly and Dashboard and Moonlight are running 24/7.  The only way I knew it crashed was the the dashboard became unresponsive and when I tried to reload Dashboard, the browser reported no response.  I can't figure out how to reboot it as nothing responds (which is what makes me think its the Pi).  I powered it down the first time by holding the power button on the Pi PCB itself.  Is there a preferable way to power down when it has crashed?  What is causing this?  Myserver6 is the only thing running on this Pi.
Thanks,
 

I can't teamviewer into it. can you see it on your network? you could try to shell / putty into it from another PC on the network and do a sudo restart
www.onlogic.com/company/io-hub/how-to-ssh-into-raspberry-pi/

Hi David;

I can't do any of this because the Pi is totally unresponsive.  The only thing I can think to do is to shut it down with the power switch.

Do you have a monitor on it? If so power cycle to see if it gets through the boot process.

Yes a monitor, keyboard and mouse. I just power cycled the Pi and it is back up and running again.

Ok, I'll remote in  and look at log files.