Bob, check a couple of things in the HTML Editor:
On the top menu bar, find Tools, then Preferences, and having the General tab open, make sure that your initial doctype is HTML5. Then go to the tab saying Browser testing, and see if the Internal preview is set to IE9, if it's not, change that. After clicking ok you need to restart the Editor.
When it is open again, open the file you are working on and see at the bottom, somewhat over to the right. There is a wee pic of a chain. If it has a red dot, then click on it to make it green.
See if this helps.
But as said, having a look at your files would help.