Unable to Save Spreadsheet

Unable to Save Spreadsheet

I am constantly receiving the below error message when trying to save a spreadsheet whether from work or from home.  This has been occurring for the past several days but also occurs intermittently since we've started using this product the end of last year.

Error:
Unable to save.  The document exceeds the prescribed size limit (i.e., 65536 rows and 256 columns per worksheet or 1 million cells per workbook).  Please reload the document to continue working.  The data entered in the last few seconds will be lost.  Therefore, we commend that you copy the data and paste it elsewhere.
End Error:

The spreadsheet has less than 80 rows in it and less than 20 columns.  There is only a handful of tabs in the workbook which are the same size so the rows/columns/cells limit has not been exceeded.