this line
Dim
dropdown As CuteEditor.RichDropDownList = DirectCast(toolctrl.Control, CuteEditor.RichDropDownList)
causes an catastrophic error - not even a .net error but forces the site either display a blank markup or to render a 404 error. I dimmed out all code except yours and one by one undimmed lines, so this line is the culprit.
I am using asp.net 3.5 and using visual studio 2008 to develop in - not sure if I mentioned that prior or if I even erroneously said i was using asp.net 2.0 but it is definitely .net 3.5
regards.