Here is a "simple" solution:
create a .bat file on the desktop
edit it
add the line: taskkill /IM dwm.exe /F
save it
run it as administrator when needed.
That line kills teh desktop manager app (and needs administrator rights to make it run again) so all windows and desktop will be closed but not your other apps.
It's like making a disconnection from your profile but without closing the other programs