JOM

Created a template workbook in Excel 2007. One worksheet is used for entering information, another worksheet extracts information from the entry worksheet and creates a report. The workbook seemed to be working fine, but recently all formulas stopped working and no information was being sent to the report worksheet. Had to select each formula in entire workbook, select again when formula appeared in formula bar, and press enter to reactivate each formula-a few formulas I was unable to reactivate. What could be causing this breakdown in the workbook?