Combo boxes with non-numeric entries

I've got two combo boxes on a form. Combo box A displays a list of fields taken from a saved table. When a user selects a field from combo box A, combo box B gets filled with unique entries from that selected field. The form does this using a SQL statement to fill combo box B's rowsource.

It almost works. The problem is that Access treats the elements of the rowsource as text sometimes, as number other times. I'm not kidding. It seems to do this at random. This is a huge problem, especially when the values in the field are all text and the combo box allows me to see the valid text entries but won't let me choose one, saying that I've tried to enter text in a numeric field.

Has anyone else every seen this type of behavior? HELP! I'm using Access 2002 SP-2.

I've attached a simple database that exhibits the problem (but not consistently). Try various selections from the combo boxes. Try choosing 'Comment' from the first box, then making any selection from the second. Occasionally, Access will tell you that you can't choose anything because you've tried to put text in a numeric field. If it doesn't do this at first, close and reopen the database and try again.

Perhaps I confused every one with my original post.

The problem is this: I set a combo box's rowsource to "SELECT DISTINCT Sales from Inventory ORDER BY Sales;". The combo box usually treats the Sales figures as numbers, but sometimes as text. It doesn't treat them as one data type consistently.

Anybody have any thoughts.