Originally Posted by Macnemarion
I have this issue all the time. I used to just reboot to fix it, but on my machine I found that if I hover over the show desktop square in the far right of the task bar it returns to normal.
Don't know why it happens but it does.
You my friend, are a genius. I know I am some 3 years late but this still happens, on Windows 10 too. So hopefully this helps others.