see alot of people having trouble accessing the Host file (C:\Windows\System32\Drivers\Etc\hosts)
If for some reason it wont let you open or save the file, go to "C:\Windows\System32\Drivers\Etc" and right click the "Host" file, click properties, now uncheck "Read Only". There should also be a securety tab. Click that and give yourself full access to the file.
Go into the file, change what you need, save and quit. Then go and change the securety setting back, its set there for a reason.
Hope this helps those of you having that problem.