seeing hidden lines in no hidden view

I just started using Creo2 about a month ago and I'm having an issue with the no hidden view. For some reason, I am seeing the outlines of threaded holes in my no hidden view. The lines are purple. I have a couple of other parts that I have imported as an .igs file and they are acting similarly. Does anyone know what the problem might be. I don't want to see the outline of threaded holes in my no hidden view.

Any help would be greatluy appreciated.

August