Problems after setting properties to "big fonts"

After I changed my properties from "little fonts" (96 dpi) to "big fonts" (120 dpi) one of my forms doesn't look as I designed it. All other forms keep their appearance. In this specific form I have a tabcontrol and therefore I think that this may cause my problem.

Within my first tabpage I have a treeview and some textboxes, labels and so on. But my controls aren't visible, not at runtime and not in the development. They changed their location and now they are somewhere out of sign.

Has anyone an idea or does anyone know if this is a bug?