Word 2013 won't open random files at random times. It starts but is blank.

[dalearyous]

hard to explain, when i double click a word document word starts but then the window never comes up. it shows up in the taskbar on the bottom of the screen and if i hover over it i see the document has started but its blank and won't come up. sometimes if i try to open it 10 times the 10th time will work, sometimes not. no rhyme or reason for what files open and what don't.

wtf?