404 Errors on jQuery Files that Do Exist

I have been beating my head against a wall and just cannot figure this out so I am hoping someone can. I am using WordPress 3.8.1

When using YSlow (with Chrome and/or Firefox), I receive a 404 error on three jquery files:

https://mysite.com/wp-includes/js/jquery/ui/jquery.ui.core.min.js?
https://mysite.com/wp-includes/js/jquery/jquery.js?
https://mysite.com/wp-includes/js/jquery/jquery-migrate.min.js

I have checked in the file directory and those files do exist.

I have the same EXACT website duplicated on a sandbox domain and I am NOT getting the 404 error on those file when using Yslow. Now, when I say exact, I mean the version of WP, the theme, plugins and database. The only difference in the database is the URL of the site.

I had hoped to duplicate the error in my sandbox domain so I could possibly figure out what is going on but there is no error there.

Any ideas?

Thanks much!