Hi:
I assume you have rebooted your computer since the problem started, if not reboot and try opening and closing the file.
First there is a vary small chance (I have had it happen) that a badly formed cell formula crashes the sheet when saving if you have recalculation set to manual with the box checked to recalculate before saving. If you do un-check the box and try saving. You can also test for this error by forcing a complete recalculation by pressing CTRL-ALT-F9
Try the following: (they all assume that there is a problem with the original file and saving in a different format will fix the problem.
1. Try a "save as" (immediately after opening file) and change the name as opposed to just a "save"
2. Try a "save as" to a completely different drive (probably best if you use the root drive of your laptop.)
3. Use file explorer to copy from the shared drive to your local drive and then try opening the file from the new location.
4. Try saving it in another format such binary XLSB, or just XLS (assumes your normal saving format is XLSX)
5. Try opening and saving it in libreoffice.calc (you can download a copy from libreoffice.org) then try opening and closing it in Excel
Finally open your backup copy and see if it has the same problem. (which I hope you have). if you don't have one then try and copy and paste each sheet into a new workbook.