#Error in fields on a form subreport

[Market man]

I have a datasheet subreport that displays sales for every day e.g.
Monday, Tuesday, etc.

A total field displays totals from a SELECT query

e.g. SELECT (Monday+Tuesday+Wednesday) AS Total
Error checking for null and empty and numeric values is performed
already.

This all works fine on the development machine Windows XP Home, Access
2002 - total field displays
correct totals
I copy the .mdb database across to the office machine, Windows 2000
Professional, Access 2002 (exactly same version as the development
machine)

Total field now displays #Error.

It works fine on development machine so it is not an error checking
problem.

#Error also displays on a different subreport using a simple function
like MonthName(Month)

I have checked all references and none are missing. 6 references are
selected on the development machine and EXACTLY the same 6 are
selected on the office machine (have tried deselecting and reselecting
them - problem remains).

What's more, when I close down the form with the #Error field
subreport on and reopen it on the office machine, the #Error sometimes
disappears and the correct total appears, seemingly randomly.

Print preview and printing displays the correct totals with no #Errors
i.e. #Error displays but does not print

Can anyone help?