To stop having to keep re-authenticating while working in Virtual Server without using SSL, add the URL to your Intranet security zone in Internet Explorer.

In IIS Manager on the Virtual Server:
- Open the properties on the Default Web Site
- Click the Directroy Security tab
- Click Edit in the Authentication control box
- Check Basic authentication
- Uncheck Integrated Windown authentication

Now when you use Virtual Server you should only have to authenticate once.