ToolsOptionsCalculation can be Auto or Manual.

Excel takes the Calculation mode each session from the settings on the first
workbook opened in that session.

i.e. If you saved Book1 with calc mode in manual and opened it first, calc
mode would be in Manual.

If you saved Book2 with calc mode in auto and opened it after Book1, Book2
would be in manual mode(Excel ignores the auto calc mode in this case).

If you close Book1 before opening Book2, Book2 will be in auto calc mode.

Confusing enough? <g


Gord Dibben MS Excel MVP


On Mon, 30 Nov 2009 18:14:01 -0800, hilger2000
wrote:

Why does the "automatic calculation" setting occasionally switch to manual
without me knowing? Excel 2003 did this, now 2007 is also.