Well, I just posted this in another thread but I thought I should toss it out here and see if anybody can solve this issue:
I've been having this problem too. Win+M is a good workaround, but that's significantly more difficult to do with only my left hand, and I've gotten SO used to using Win+D, I seriously do it ALL THE TIME. I downloaded the Dark Industry DesktopX theme and for some reason Win+D would work (as in hide everything except for the objects. It had the "Hide windows desktop" thing checked so there was no icons, and if I Win+D my actual desktop with the icons on it would flicker for a sec but then it would still show the blank one, but it would keep my widgets and objects. (Which is exactly how I wanted it to work.) Then I restarted my computer and it no longer works. Win+D now minimizes my mainbar object.
Also, this theme makes it so that when you right click on the desktop, instead of getting the normal menu, you get basically a start menu. Where is the option for that? I think it may be significant.
I'm just trying to describe everything as accurately as possible so that perhaps somebody more skilled than I can figure out why it was working before and hopefully we can replicate that.