You cannot modify the Hosts file or the Lmhosts file in Windows Vista

You cannot modify the Hosts file or the Lmhosts file in Windows Vista

WORKAROUND
To work around this issue, follow these steps:
1. Click Start Start button , click All Programs, click Accessories, right-click Notepad, and then click Run as administrator.

User Account Control permission If you are prompted for an administrator password or for a confirmation, type the password, or click Allow.
2. Open the Hosts file or the Lmhosts file, make the necessary changes, and then click Save on the Edit menu.