I've had my d2 for a total of less than 24 hours so far but its been actin funky by flippin the screen in the opposite direction of the slide out keyboard. Also there's no slyde preinstalled for the keyboard which made me mad.
I don't think your phone is doing anything out of the ordinary. Under settings/display - I have auto-rotate checked. The display will rotate depending on how I'm holding my phone, except for upside down. This is perfectly normal.
What do you mean when you say there is no slyde preinstalled for the keyboard?
I've had it get 'stuck' in portrait mode for the Home screens, even while the browser and other apps are in landscape mode. I also tried using a rotate widget to force it and it would not work on the Home screen. It looked like it was trying to rotate but came immediately back to the portrait. A full power off and reboot does not cure this problem.