Hi Ken. That is really smart and something I wouldn't have thought of. However, that was not the issue, but it did give me an idea. I opened up a different project and it worked fine. I can only conclude that the file I was working with was somehow corrupt. Thank God it wasn't anything I put a lot of time into and didn't loose anything significant. I am still convinced it was a Windows thing and not Sonar.
I have learned over the years and can't stress hard enough how important it is to save and back up a project frequently. In fact, I save my projects every time I do anything to it. While I find Sonar to be stable, I can't say the same for Windows. I even survived a lightning strike once and the subsequent power surge before I could shut things down, because I save my work religiously. Thanks for offering your help.