It’s a problem with Norton confirmed…Norton is firing a “false” positive on a js issue…
Norton will give you a “Warning” that there has been an intrusion attempt
“on whatever” program was running at the time (in this case, you’re trying to use the Visual Editor in WP with either IE or Firefox)
***Here’s the fix, until Norton fixes the issue with their next update…***
Disable Norton’s Intrusion Detection feature…You can pick a time 1, 2, 5 Hrs, or Permanently…
Close down your browser, clear your browser cache, log back into WP Admin Panel, to to Manage Posts or Pages, and the Editor should now be working…
~AzSno…