Hello and welcome.
I'm not familar with nxc files or Hero Engine. Had to do a search. Seems they are associated with a programming language and a development platform.
Before you reinstalled W7 were you opening the ncx files with Hero Engine? If so, and if it's not working now, try reinstalling Hero Engine. Also look to see if there are any plug-ins you missed.
While you're at it, check the Device Manager to ensure everything is good.
- Click on the Orb which is typically located in the lower left corner.
- R-click Computer
- In the left-hand pane, click Device Manager
- Check to see it there are any yellow or red marking associated with any of the devices.