Access2000 Form Oddity

I use a subform that is a continuous form that gives users an Excel-like interface. I have a problem that you can view with the attached GIF file. When the user selects a particular field (which is a combo box) in the first record, all of the subsequent (same field) become blank. The data is still there; if I click on a subsequent record, that data is displayed correctly. But the data in the first record becomes blank. Again, the data is still there, it just doesn't display.

Sorry if this is unclear, but it's a bizarre problem.

Thanks for your help.