Unfortunately. I have the power-on problem even with an empty SD card.

It certainly seems like the N800 does a bunch of checks when the power button is pressed and if it doesn't like what it 'sees', it simply refuses to boot.

Hopefully this is a software problem, as has been suggested, and that it can fixed with an update.

I wonder what percentage of devices are doing this and how many are being returned to Nokia. Perhaps not enough for them to get a fix out quickly!