Form works in Access 2007, but not the 2007 Runtime

Hi. I have a simple Access form which works fine on my development computer
running Access 2007 Professional. But when I package & deploy my app to a
computer running only the Access 2007 runtime, the form crashes with the
error "Execution stopped due to runtime error".

The form contains a button and an image control. The button's click event
opens a file dialog, which the user then uses to select an image. Upon
selecting an image a record is saved to the database and the image control
displays the image.

Users can select images just fine, but when they RE-ENTER the form and the
image attempts to display in the Image control, it blows up.

Why does this work ok in Access 2007 Pro but not the runtime? Are there
missing registrations/components, etc that may be causing this. Please let
me know if you need to see my code.

Thanks (and help please) !