Oh hi Mart!
Just wanted to let you know that this is one of the most clear and detailed help request I've seen.
It could be a bug but since I'm not on the LL team and specially not a programmer, I would just ask if you perhaps installed apps that could change how the desktop environment reacts?
For exemple, a desktop switcher or manager, something that could "manage" active tasks or maybe transfer them to desktop 2,etc. (i.e. You can have multiple desktops in Linux).
Oh, or maybe you changed Kernels manually?
A far fetched idea would be to try a different video driver... but I wouldn't bet on that.
We'll, I'm going back to work now, see ya!