I rode my bike to LBS yesterday and had them look at bike. Actually, I was hoping I wouldn't have to ride to LBS, but it still wasn't shifting correctly and very loud! Anyway, it appears the problem is in my shifter or cable housing -- more than likely something in shifter broke, causing it not to sit right on cogs. If it is the cable housing, it means the cable/housing got contaminated, not allowing proper shifting. Good new! everything is fixable ... just need time for diagnosis. I will know more Monday afternoon after I pick it up.