Sean,
People running Vista and Windows 7 are having problems getting the program to work.
One problem is that it prompts the user for WAV files, then apparently does a copy and rename, placing them into the "programs" subdirectory of Harman International\How To Listen. This is a no-no under Vista and Windows 7. Microsoft has protected the Program Files and Program Files (x86) directories and their subdirectories in Vista and Windows 7 so that only programs running with administrator privileges can do such writes.
The workaround I use is to create a directory under the root called something like "Old Programs", then install each such misbehaving program into its own subdirectory under that. A user-created directory such as "Old Programs" does not have the protection that Program Files and Program Files (x86) do, making it okay for a program installed under "Old Programs" to write files to its install directory or a subdirectory of that. This worked for me, and also a user on another forum who had the same problem.
This is a kluge though. The correct solution is to put these files in the user's AppData folder. When this is done, each Windows user has their own unique AppData folder assigned to them at login time, making the program's self-contained multiple-user login feature (which has the password bug as has been noted elsewhere) redundant. This solution should work under XP, Vista and Windows 7.