Talk to forums, cursor jumping backwards

I posted this last year
the problem still exists and it happens every time i post in a talk to forum
basically what seems to happen is that the cursor will jump backwards one space every so often as i write.
this results in a load of gobeldygook when i look up onto the screen
i am running on a windows 10 pc and using internet explorer
not noticed this on any other platform

here is an example screengrab video i just took