Does anyone else experience this issue? The controls to interact with objects are barely working on my Mac, mostly not at all but sometimes when I move the mouse over half my desk I'm able to select something other than 'Look at'.

I'm not sure if it's the same issue, but if it's like the one I found then I would suggest making sure you're holding down the right mouse button when trying to interact with objects. If you let go during that radial menu, it sometimes doesn't function.

I'm having the same problem, it's almost unplayable. I have already contacted the devs but they didn't help me much (they said I must have changed DPI settings but I didn't).
A little help is to randomly press "A,S,D,F" keys on my keyboard which triggers the movement usually.

Really sucks that there are so many bugs in the game.

Just a quick note to say I've had exactly the same problems.

I've found a solution, though not an elegant one. Switch the game to windowed mode, and the controls work fine. I wish I knew what made it so awkward in full screen mode.

It´s a long time since you wrote this but if you care to answer, how do you change the DPI settings? What kind of setting is it?
Thank you very much in advance (to who ever answer).

I have the same problem on 64-bit win7. Controls are messed up. When I leave places/rooms and go back, it works; until it starts to bugging around again...

I'm having the same problem (OS X 10.8.5, German version). Windowed mode works but I would really prefer to play full screen...