Same thing is happening with my HXD860 which is only 14 months old! Sometimes it will also just display WELCOME with a loud fan noise. I then have to hold the power button down for 10 secs to reset it, after which it may come on and power off again, or it may just stick on WELCOME again.
It started happening after the digital switch over in my area (Beacon Hill transmitter Devon UK). I'm convinced it is related, as my Thomson box is doing strange things too.
Geoff R
May 2009