I am using windows 98 and MS Excel 97. I have a workbook having 2 sheets namely "31.08.03" and 30.09.03", in which if I rename a perticular sheet-name and press enter, it prefix ".xls]" to the sheet-name. for example, if I rename the sheet "31.08.03" as "ABC" and press enter, it rename the sheet as ".xls]ABC". Now, if I try to rename the sheet ".xls]ABC" as "31.08.03" again it shows the error message as "while renaming a sheet or chart, you entered an invalid name.Try one of the following." Please note that i am not using any special-characters in the sheet name. i have used quote marks to only highlight the sheet names. This problem is not appearing in any newly created workbooks.