Yeah I also had it when I had to switch to IE for a short while.
The exact cause is hard to pin down, but is likely due to one of the many plugins I have installed. The only thing that I can do to fix this is to remove all the plugins and re-add them one by one to try to find out which one is causing it and then work on a fix for here.
I will do that over the next few weeks but may see if I can first reproduce it on the test site, and if so, I can do the work there. Anyway you look at it, it's a long and arduous task so bear with me as I try to get the motivation to work on it.
It is on my list though