It was difficult to disable all the plug-ins on the live site without unwanted ramifications. This is where the problem was — on our live site. Until we get our DEV site up to date, I will not be able to troubleshoot using this method. Lesson Learned — do not upgrade plugins on the live site. Upgrade on a dev site first and test!
In the meantime the inner scroll bar (the one that I was having the problems with) has disappeared and the outer one seems to work – if albeit a little flakey. The only problem now is that when I open a visual editor box within a widget it goes “off the screen” to the left even when I collapse the menu. I have gotten around this by shrinking the screen (ctrl -) which I read in one of the other posts about a similar problem. so I guess for now it is manageable!