The following error shows up in my system log:

6/12/14 2:11:28 AM [0x0-0x32032].com.microsoft.Word[949] Thu Jun 12 02:11:28 slos-MacBook-Pro.local Microsoft Word[949] <Error>: kCGErrorIllegalArgument: _CGSFindSharedWindow: WID 497

6/12/14 2:11:28 AM [0x0-0x32032].com.microsoft.Word[949] Thu Jun 12 02:11:28 slos-MacBook-Pro.local Microsoft Word[949] <Error>: kCGErrorIllegalArgument: CGSGetWindowTags: Invalid window 0x1f1

6/12/14 2:12:25 AM [0x0-0x32032].com.microsoft.Word[949] Thu Jun 12 02:12:25 slos-MacBook-Pro.local Microsoft Word[949] <Error>: kCGErrorIllegalArgument: _CGSFindSharedWindow: WID 501

6/12/14 2:12:25 AM [0x0-0x32032].com.microsoft.Word[949] Thu Jun 12 02:12:25 slos-MacBook-Pro.local Microsoft Word[949] <Error>: kCGErrorIllegalArgument: CGSGetWindowTags: Invalid window 0x1f5

When I trained Microsoft's tech support engineers, nearly 20 years ago, the sovereign answer for problems like this was to uninstall Microsoft Office (or Word if you do not have the full office suite) using the uninstall utility that came with Office and then reinstall and apply all the patches. You could spend hours troubleshooting a problem like this or do the uninstall/reinstall in maybe half an hour, most of which is taken up downloading and installing all the patches. Microsoft is loathe to start a product from scratch and much of the 20+ year old code is still in Office so it is a good bet this advice is still valid.