I know you can get this kind of result if you run the UltraVNC program as an application and it is not installed with Administrator access. Try installing the UltraVNC program on the PC you are trying to remote into then reboot the PC. After that, try the connection again. I also believe that UAC can cause this problem. You might want to lower the UAC setting for testing, but I never would recommend running your PC with less than the default setting. I might be totally wrong in this, I am only trying to help.