ICE30 validates that the installation of components containing the same file never installs the file more than once in the same directory.
ICE30 goes to every component in the Component table and then determines the component's target directory from the Directory table. It then checks to see which of these components install to the same target directory. Finally, it uses the File table to verify that none of the files in these components have the same name.
ICE30 checks for both long filenames (LFN) and short file names (SFN).
What you should look for are the components that have same files and when using short file names these components installs the files in the same directory.
You can find more information and an example for ICE30 failure at
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/msi/setup/ice30.asp