I have a customer who is running Excel 2010 on Windows 7 Pro. After about six months of using this computer an issue with an Excel workbook appeared. In the workbook there are about fiteen worksheets for recording employee time. Now all of the sudden time data entered in a cell on Jane Doe's worksheet is duplicated on John Doe's worksheet. The problem is inconsistent also. There are times when the cell data is not duplicated accross worksheets. Another user who has Excel 2007 does not expereince the issue. I upgraded the workbook to .xlsx format from .xls format to see if that would help and it did not solve the problem. I am wondering if this issue is due to a bug in some update of Excel 2010 over the last month. Any help would be greatly appricated.