Possiblities:

1) The workstation has a different setting for Regional Options in the
Windows Control Panel, so the date is being interpreted differently for
their setting.

2) The workstation has an out-of-date copy of JET 4. Locate the file
msjet40.dll (typically in windows\system32). Right-click it, and choose
Properties. On the Version tab, you should see:
   4.0.8xxx.0
The xxx digits don't matter, but if you see a number smaller than 8,
download SP8 for JET 4 from:
   http://support.microsoft.com/kb/239114
(If you see a 9, you are up to date also. Windows 2000 may show this.)

3) Access is misunderstanding a date value in an unbound text box on a form,
a calculated date value, or an undeclared parameter in a query.

These articles might help:
   International Date Formats in Access
at:
   http://allenbrowne.com/ser-36.html
or:
   Calculated fields misinterpreted
at:
   http://allenbrowne.com/ser-45.html