There are a couple of "task view" type things someplace on my task bar that I seem to swipe without meaning to or wanting to, that put all my open browsers into a matrix on the desktop...another case of MSOffice getting too big for its britches, and trying to run my life when I don't want it to.
I haven't had them make a screen disappear yet, but I wouldn't put it past them....
Something like that might be happening; you can sometimes swipe an icon without even wanting to (or knowing it's there...)
You might also look up online something like, "screen disappears while I'm posting" to see if there's an FAQ on it somewhere. I find a lot of weird things that happen to me are also happening to others (most reassuring...!)
M.