[benten10]

Hopefully all the child posts will see this too.

TO edit the hosts file, you need to have admin privileges. That means closing whatever editor you're using, reopening it with 'run as administrator', and then opening the hosts file. You need to do this even if you are an admin account.

Another way to do it is to open the hosts file under normal editing privileges, editing it, saving it somewhere else, and pasting it into the drivers folder. The system will ask you if you want to run as admin, and you need to say 'yes'.

Nothing could (or should, I guess) be changing the hosts file otherwise (AFAIK, my source being many, many SO posts and random forums) without it being given explicit admin privileges when it attempts to change the file.