I made a WPF/C# program and I am using the internet control for WYSIWYG HTML editing.
it is a regular Executable program.
it works on most computers however
I had this same problem too but my issue was using TFS Build 2008. The hintpath was relative and had to be changed to the exact path. Otherwise during the build it kept picking up the Office mshtml.dll
C:\Program Files\Microsoft.NET\Primary Interop Assemblies\Microsoft.mshtml.dll