OK I've found the issue.
If you leave the precise input toolbar on and exit inventor then reopen inventor. The inputs arent available.
If you close the precise input toolbar before exit. Then exit then reopen it is fine.
So its an Inventor issue, not video card problem.
Thank you so much.
This solution works perfectly.
I continually find these types of anomolys in Autodesk producrs. We have to use this for PLTW. I'm continually suprised that Autodesk ships such idiosyncratic applications.