Unresponsive script

In dashboard > Pages > Default Templates, I choose a default template and EVERY time I get a popup box for Unresponsive Script (see attached print screen). I have clicked on Continue the script, stop the script, and debug the script, but it doesn’t change anything and I still get the same popup every time I click on the particular default template. Also, when I get the popup box, Mozilla Firefox also says it’s not responding in parentheses.
I have tried several times to clean up my computer and Restart but it still happens. Is this something wrong on HB’s end, Firefox’s end or my end? What can I do?
Thanks.
p.s. I will reply again privately with my info in case you need it.