RadRibbonBar does not modify registry entries.
You mentioned that you are using the RadRibbonBar version that comes with the VS2005 Express package, so there might be some entries added by the installer of the VS package (unfortunately, we have no control over that). Our controls do not modify registry data.
What I can suggest is the following: remove the RibbonBar from your system. If the VS2005 problem persists, we will ask you to reinstall it again. We know we should not ask you to do this, but the problem relates to your registry and there is no other way to fix it.
Please, download the latest version of RadControls for WinForms, which includes RadRibbonBar. Install it and try it instead. If all goes well, please write back and let us know.
the Telerik team