You should also have a winamp.dll in the new RideRunner directory (Or in the Plugins sub folder). It is probably just a conflict with the same dll being registered in 2 different places.
Make sure you have a Winamp.dll in the RideRunner folder or in the plugins folder then simply register the DLL in the RideRunner directory. It's also best if you unregister the old Road Runner folder DLL before deleting that directory just to keep things neat and tidy under the hood.
I have attached a .rar'd windows registry tweak below. Unrar, then just double click to add it to the registry. This enables registering a dll by simply double clicking on it, or by right clicking on it and choosing register or unregister from the context menu.