Try using the following method.
Windows key, find & right click "Notepad" --> Run as Admin.
(Do not close the notepad!!!)
On the same notepad, tab under file, open, C:\windows\system32\drivers\etc folder and modify the Hosts file as desired.
Save it on the DESKTOP. (It will not allow you to save it directly to the etc folder.)
Copy & Paste the saved text docs from desktop to C:\windows\system32\drivers\etc folder
Hope this helps.
B.