This is usally a .Net Framework cache problem.

Try this:

- Close you VStudio
- in the TaskManager, stop your Aspnet Process (it will restart automatically)
- go to C:/WINDOWS/Microsoft.NET/Framework/v1.1.4322/Temporary ASP.NET Files/ and delete everything
- open you VStudio project, rebuild and check if the CuteEditor.Dll is in the Bin directory (also check if it is in your reference list)

This should solve the problem.

Let me know if this worked.