I have a simple spread sheet involving a 50 Column by 50 Line Spread sheet involving No Macros and nothing more complicated than simple "IF" statements and 2 Dimension Product Sums. The sheet which has functioned normally for over a year suddenly, today, October 15, began generating the following error message whenever a cell value is changed. "Excel ran out of resources while attempting to calculate one or more formulas. As a result, these formulas cannot be evaluated." Pressing "OK" simply causes the message to be regenerated ad nauseum.