> The web  format has recently changed again and I can now give further
> information.

I still find it quite unusual that a web format  would change. This would
require that the web programmer change the programming, for no apparent
reason. I really do suspect that the problem  is at your end. What is the
web site and where are the dates that you put into FN?

> ... because the date  format for
> column FN is set to dd/mm/yyyy.

You don't actually set the date format for a column. You can set the
DISPLAY format, but this doesn't change the way Excel will convert typed
dates to its internal format.

E.g. if I format E13 to mm/dd/yyyy and then enter 12/10 (remember that I'm
in Australia), then this is interpreted as 12th October and the cell
immediately displays as 10/12/2008. E17 has =E13 but is formatted as
dd/mm/yyyy and shows me 12/10/2008.

I.e. the input conversion is done according to the locale setting - not the
cell's format.

However, if I enter 10/13/2008 in E13, Excel will store the value as the
string "10/13/2008" (left justified) and this same string displays in E17
(again left justified). Although this string has not been converted to
internal date format, Excel will still use it as a date in certain
circumstances, and will then treat it as 13th October.

You will need to point us at the source web site and also upload the
offending workbook so we can have a look at them.