I have a workbook (format .xlsm) that used to work fine on my computer, but now something has happened. When I try to open the workbook, it briefly opens, and then Excel closes. I went to my local public library, and on one of their computers, the same workbook opens and runs just fine. Are there any general things to check when a workbook opens one day but not the next? I have not installed any new software on my computer. Thanks.