Yes, I learned that if you add a light but turn its shadows down to 0%, then the shadows won't appear. Apparently they are there by default in V5.0? Also, I've been running Rhino for Windows on a Mac via Parallels, and McNeel says this is unsupported. And considering that the only major issues I've ever had with Parallels are video in nature, I wouldn't be surprised that there are some issues I'm having simply because of this.
Overall though, I think I have things working the way I need now. Thanks for asking!