I currently run MS Office for Mac 2016. I have used Excel and Word for many years. For weeks now I frequently have been unable to open a Microsoft Excel document when I already have one or two open. I see the little burst of the image, but the document does not open. This has been happening intermittently for many weeks. Software updates have not fixed the issue. A Force Quit report to Microsoft did not yield a fix for the issue with the next update. I have not been able to identify a pattern that might be at the root of the problem. My attempt to get help from Microsoft this a.m. indicated I will get a callback in approximately 16 hours.