Try selecting all the cells
edit|replace
what: = (equal sign)
with: = (equal sign)
replace all

Then test it out to see if excel woke up.

wrote:

If I type in 1 in A1 and 2 in A2, then type =A1+A2 in A3, the result
is 2.
But if I change A1 to, say, 5, the new sum should be 6. But it
remains unchanged as 2.
It is not due to the options being set to manual calculation and it
only does it occasionally.
F9 does not change/update the cell(s).
Only solution is to press F2 and enter for each and every cell, or
reboot - a few times.
Is my spreadsheet just too big? If so, what else can I do without
reducing the file size?
Thanks.

--

Dave Peterson