Using Update 13 on windows 7 and 3 monitors.
In this case microstation is stretched across 2 monitors, my custom ribbon stretches across into the second monitor, if I then maximize microstation (In this case causing it to shrink down to one monitor it will crash microstation. If I manually size it down to just one monitor it is fine as the icons re-size to adjust for the small screen size.
Is it possible for you to supply a screen capture going across all monitors what you have configured with your ribbon menus. We can then try to replicate what you are describing and raise a defect if required.
Regards Andrew Bell
Here is a screen capture of the ribbon
I'm sorry but the quality of that image is extremely bad. Can you provide a screen capture with better quality.