With those tools you can also check which files are loaded, "Net" tab or something. Prepare to fall off chair, can be very ugly but report back to plugin dev(s). for fixes if you can narrow it down enough to be sure.
Yesterday I had same issue and started to exclude plugins one after another, from no. 53 to 1. Well I did first check for active files so many were excluded alreday but still a very annoying task. 100% failure though! Turned out issue was my own jQuery script doing something. Not really mine, nicked from the internet. Problem was only present in a shortcode plugin which use custom post type so same post.php url as if you were editing in a regular post/page. This trigger certain activity, including Suffusion. Problem was this script was looking for an #excerpt element but as not finding any it gave error and random luck in clicking buttons in that shortcode editor. Even WP sidebar stopped working or the fly-out part did.
Actually real issue was the little snippet was dumb as a door and expecting that element to be present. If not chaos. So solution is to make sure that never happens and script die if no #excerpt. Much the same logic as for plugins and themes when they should only load own scripts/css when required. But I did not know this jQuery behavior, copy/paste from internet disaster no. 234
Also I mention error console because if I had used brain that would have pointed me in right direction in 20 seconds. Just happens that particular shortcode plugin has a history of conflicts, I have reported 2 my self, so I was locked on the idea that I found yet another. Most devs. are happy to get such reports, better than you publishing "it sucks!!!", so dont hold back.