'k, hangs and reboots - seen these...

What I have noticed is N800 if overly stressed (too many web pages); and subsequently tablet reboots, some strangeness can be seen with settings - eg bluetooth turning on, when previously set to off. Never been an issue - setting change is obvious and easily changed back...

The setting change that seemed to be cause of instability - tablet stopped asking for device lock code on booting - just booted straight in. Stability seems restored by changing device lock code in settings (no need to use new code - reentering current code sufficient). Tablet then begins requiring code on boot as expected.

Perhaps the lack of asking for code on boot would be obvious to everyone else - for some reason it took me a bit of time to notice change. Doh... Thankfully noticed before reflashing tablet - doesn't look like reinstall now needed.