Worked like a charm. Solidworks does not like internet explorer 11 and the linking of it stinks.
I had come across this several times when IE11 decided to update itself. Always just uninstalled, even though SWX16 64bit SP4.0 requirements says supports IE11. I got tired of having to do this, so tried this fix, and it worked! I had 2 files to double extension, but started right up after I changed the 2nd one.