Sounds to me as if the query that is the Row Source for the combo box has an
error when trying to use a function that is one of the query's fields.
Often, this can be because a Null value is the value of a field that is an
argument for a function that is being called.

You will need to check the query to see which functions it may be using, and
then check your data.

--

Ken Snell
MS ACCESS MVP

"Tim" wrote in message
...
I have an Access 2000 backend database on a Windows 2000
Small Business server. Front end is an MDE database. I
have a subform with a combo box that works fine on the
front end when working on the server, however when working
in the front end on a Windows XP computer the combo box
gives me the "invalid argument" error and there are no
options in the drop down box to select from. I have other
combo boxes on the same subform that work fine. Any
thoughts? Thanks.