Try the last option on this page and see if it is likely to be your issue:-

http://www.decisionmodels.com/calcsecretsf.htm

--
Regards
Ken....................... Microsoft MVP - Excel
Sys Spec - Win XP Pro / XL 97/00/02/03

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It's easier to beg forgiveness than ask permission :-)
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"Schumi" wrote in message
...
In large workbooks ( 10MB) I found that often Excel does not calculate. I
have to enter the cursor in the cell (or the formula bar) and press enter,
so
that the formula is recalculated.
However, my calculation is set on automatic (Tools/Options/Calculate
etc.).

Does somebody know why this happens and has an answer?