Safari 9.1 Stops Responding to My Input
I'm using Safari 9.1 with Yosemite (10.10.5) on a 15" MacBook Pro with Retina Display. Since updating from 9 to 9.1, I've repeatedly had the experience of Safari looking normal but not responding to keyboard commands or normal mouse clicks. I can scroll pages (and scrolling items on a page can be scrolled normally), and the cursor changes to the appropriate pointer over links, but I can click 'til the cows come home and NOTHING will happen. Right-clicking gives me the usual pop-up menu allowing me to open a link in a new tab or window, and if I go that route the link will open properly... but with the same maddening lack of response.
I have been unable to predict when this problem will be triggered. It thought it was linked to how many cookies have been collected, but sometimes happens when I've got about 60 cookies (my usual browser "baggage") and sometimes happens when the count is close to 400. I've tried disabling all plug-ins and it hasn't made a difference. The only way to return to normal functionality is to quit from Safari and then start over -- and when I re-open the same page of the same site on which the problem occurred moments earlier, all is copacetic and I can browse the web normally until Safari suddenly decides to ignore me again. I do not need to force-quit the app when the problem occurs because as far as my Mac is concerned Safari is running A-OK.
I've begun using the Mozilla browser a lot more (it never has the same problem) but I'd like to be able to use Safari without worrying about having to quit & retrace my path several times. Has anyone else encountered (and hopefully fixed) this problem?
MacBook Pro with Retina display, OS X Yosemite (10.10.5)