I tested the scenario that you describe by placing a RadMenu and a RadRibbonBar control in a simple table but I am not able to replicate the appearance that you describe (see the attached file). Can you please provide the markup as well as any custom style that you might be using so I can test the issue locally and help you out?
All the best,
Kate
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed now.