Blank con-box after upgrading from Access 97 to Access 2002

[Gerry]

After converting an Access 97 database to Access 2002, a
combo became blank. The combo-box does have content
because the drop-down list can be scrolled but it is
usually invisible. Occasionally it is visible. What could
be causing this schizophrenia? I need HELP!

Below, are the specs of the combo-box.

The Row source type is Table/Query

The row source of the combo-box is:
SELECT "From " & Format([StartDate],"mm/dd/yyyy") & "
to " & Format([EndDate],"mm/dd/yyyy") & " in " & Trim
([City]) & ", " & [StateCd] & " " & Trim([Countries].
[CountryName]) AS SessionDesc, Sessions.SessionId,
Sessions.CourseId FROM Sessions LEFT JOIN Countries ON
Sessions.CountryId = Countries.CountryId WHERE
(((Sessions.CourseId)=[Forms]![frmCourseView].
[CourseId])) ORDER BY Sessions.StartDate DESC ,
Sessions.EndDate DESC;

The Column Count is 3. There are no column headings.

The "SessionDesc" has a column width of 2.5" and consists
of a concatenation of various data-elements of the
Sessions and Countries tables plus the literals "from",
"to" and "in".

The Sessions.SessionId is the bound column and has a
column width of 0.5". Its data-type is AutoNumber.

The Sessions.CourseID has a column width of 0". Its data-
type is Number.