I am using Excel 2013 via Office 365 and it's the damndest thing but when I put my laptop to sleep and it goes into hibernation when I resume windows all of my excel windows are invisible. They show up in my taskbar, I can 'maximize' them, my cursor changes as I go over cells, I can press alt and bring up all those shortcut letters at the top, but the window is completely invisible. Meaning I can see whatever is behind it, thunderbird for example, but I can't click on it because the invisible excel window steals my mouse clicks.
I can open a new excel window and it shows up just fine, I can close the invisible ones down and they save dialogue box comes up just fine, but outside of that I can't do anything to bring it back.
Any ideas why?