A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Do you get the error when you open any of the Workbook or is it specific to one particular workbook?
Do you have any codes enabled for the workbook?
Try opening Excel in its application safe and then open the file from within Excel.
Click Start > Run > Type 'excel /safe' (Without Quotes and note the space in the command).
If you are able to open Excel in application safe, disable add-ins for Excel and check if it works.