When inserting lines (rows) in a spreadsheet, I get an "Excel Not Responding" message. The new line eventually appears, but it is excruciating waiting for such a simple task, especially when I need to add many lines (rows). I have performed both the quick fix and longer fix options to Microsoft office, including re-installing Office 2016, but to no avail. Microsoft suggested that perhaps my security software is running a virus scan in the background, but I can't verify that or turn it off. Help!