I received a response from support that led me to the solution. Thought I would post it here for anyone else that may run into it.
This error can occur if Internet Explorer is not installed, or if the .hta file association is corrupt (it should be set to open with "C:Windowssystem32mshta.exe").
It has previously been brought to our attention that some versions of MICROSOFT VISUAL STUDIO my 'steal' the assignment of the .hta file
If this does not solve the problem, then please run the "TriDef Diagnostic Tool" from Start > All Programs > TriDef 3D > Utilities.
A diagnostic code will be displayed after uploading the results. Please quote this code in your reply and we will investigate the issue further.
Turns out I do have Visual Studio 2012 installed and this was the problem. When running the application Windows was popping up the 'select a program to run this with dialog'. In the 'view more' I was able to manually select the html application option and run it with that. I hadn't twigged that it was missing the appropriate file association.