Hi Sandy,
Not quite on it's own.

The first workbook to be opened is what determines your setting for automatic
or manual calculation. You can change it anytime, but if you don't save your
first workbook opened it will revert back. Workbooks in your XLSTART
directory such as personal.xls and hopefully it is the only workbook there
are opened first. Window, unhide/hide file

You can have a macro or an addin turn off calculation and not turn it back on
particularly if the coding aborts and no provision was made for abnormal
terminations.

The fastest way for me to set calculation back to normal would be to use
my TRIMALL macro on a single cell as it will turn calculation on when if
finishes, I just added code to tell you if if was OFF to begin with.
http://www.mvps.org/dmcritchie/excel/join.htm#trimall
I added that because it is a macro I run frequently and I already have it
set to turn event handling back on if an Event Macro messed up, and
it was already turning calculation on -- so I added the MsgBox warning
if calculation had been OFF when macro started.

If you can't identify when the problem is actually occuring it might help
to modify your Auto_Open in your personal.xls which would normally
be the first file opened. Then maybe you will remember what you
did in the last Excel session.
http://www.mvps.org/dmcritchie/excel...esp.htm#addins
---
HTH,
David McRitchie, Microsoft MVP - Excel [
My Excel Pages: http://www.mvps.org/dmcritchie/excel/excel.htm

"sandy" wrote ...
undet tools, options, calulation tab, sometimes it changes from
the default automatic to manual. why?