You cannot modify the Hosts file or the Lmhosts file in Windows Vista, Windows 7 and Windows 8

Symptoms

When you try to change the Hosts file or the Lmhosts file in Microsoft Windows Vista, Windows 7 or Windows 8 you may receive an error message that resembles either of the following.

Workaround

For Windows 8 follow these steps:

1. On the Start screen, right click and choose All apps located at the bottom right corner.

2. Look for the Notepad application and right-click on Notepad.

3. At the bottom left corner click Run as administrator.

Note: If you are prompted for an administrator password or for a confirmation, type the password, or click Allow or Yes.

4. Open the Hosts file or the Lmhosts file, make the necessary changes, and then click Save on the File menu.

For Windows Vista and Windows 7 follow these steps:

1. Click Start  , click All Programs, click Accessories, right-click Notepad, and then click Run as administrator.
   
    If you are prompted for an administrator password or for a confirmation, type the password, or click Allow or Yes.

2. Open the Hosts file or the Lmhosts file, make the necessary changes, and then click Save on the Edit menu. If using Windows 7, you will need to click Save on the File menu.