Win 98 to Win XP conversion - date format problem in mail merge

Since upgrading from old laptop (Windows 98) to new laptop (Windows XP), my
mail-merge letters are doing strange things with date formats.  For
instance, my reminder letter for lapsed subs carries the 'expiry' date as a
merge field from the database, and this previously was shown as dd/mm/yy (UK
format).  Now it persists in showing as mm/dd/yy.  I've gone to the Windows
Control Panel and made sure that my Regional settings show UK format, even
deleted the option for US format!  On the database the date format inputs
correctly, but the mail merge doesn't!

I can't send letters out with this format, as we don't read dates this way
in UK.  For instance, someone whose subs expired on 1st October 2003
(01/10/03 in UK format) would get a letter saying their subs expired on 10th
January 2003 (10/01/03 in US format!)

I've even tried amending the input mask for dates, but the mail merge letter
still shows 'expiry' as mm/dd/yy.

Can anyone help me sort this out?

Many thanks

Ishbel Kargar