I started having the problem where quick nav wasn't working
at all. I took a look around and discovered that there had been
an extension installed called Lightning. I looked into it and
decided I didn't want it. I removed it and now my quick nav
extension is working perfectly.
You might want to see if you have this extension installed
and ifg you do remove it. I bet your quick nav will start
working again. You could just disable it to test this first
before removing it.
