Form display problem

Hi,

I have a problem with one of my applications.

It has a MIDI form and some child forms that i display when needed. The problem is that when the child forms are displayed the content of that child form is not displayed correctly.
Controls are missing or are displayed in random places, borders are missing,
text form comboboxes is missing (the date is still there) and when i scroll my mouse over, the text appears, then disappears again. Same for the other controls.

This error only happens on one computer. I wasn't able to reproduce this on any other machine.

Do you have any ideas on why this is happening or how to fix it?

Any help is much appreciated
Thank you