This is for when you have KeyShot 6 and only IronCAD 2017 installed. Currently with this setup KeyShot won't startup standalone but will startup if launched from within IronCAD. To fix this:

Go to the Windows Control Panel, System, Advanced system settings.

Click Environment Variables.

Under System variables, look for Path. Select Path and click Edit.

Add the path to the IronCAD bin folder (typically C:\Program Files\IronCAD\2017\bin) to the end of the path entries. (notice a semi-colon seperates each path entry).