Found it.

http://answers.microsoft.com/en-us/insider/forum/insider_internet-insider_spartan/edge-browser-hijacked-unable-to-reset/1768f671-90d9-4dfb-88c5-679a3664634a?auth=1

I have this same exact problem. It's as if the browser was hijacked, but there's no way I can see to fix it.