There are two main causes of monitor calibrations hanging on a specific color when you are going through the profile process. The first is a feature built into many newer displays called DDC, Display Data Channel. The second is the newer security features that are included on the Vista or Windows 7 Operating System.  

DDC causing calibration to Hang
Signs to watch for that can be symptoms that the DDC is affecting your display would be if your calibration is hanging, if you notice the brightness and contrast levels are changing automatically without you manually making these adjustments, or if you are trying to run the ColorMunki software in the Advanced mode but the adjustments for Brightness and Contrast do not populate the issue may be that your monitor has what is called DDC features. To prevent this please open the interface of your software, go to File then Preferences. Here you will want to make sure there is no check mark in the Enable DDC Calibration box.

Now when you run back through the profiling process you will be able to see the options and the program will prompt all the colored patches on your screen where before you may have only seen gray or red.

Here is some background on DDC controls. Per Wikipedia, Display Data Channel or DDC is a digital connection between a computer display and a graphics adapter that allows the display to communicate its specifications to the adapter. It allows a computer with a suitably designed graphics adapter to adjust monitor parameters such as brightness and color balance, or to initiate degaussing. DDC/CI monitors are sometimes supplied with an external color sensor, to allow automatic calibration of the monitor's color balance. That being said, most DDC/CI monitors have a setting in the on-screen menu that you can either choose to disable or enable this feature at the monitor level itself. 

If you are running Vista or Windows 7 please click here for further instructions.