Error message when you open a Web site by using Basic authentication in Expression Web on a computer that is running Windows Vista: “The folder name is not valid”

When you open a Web site by using Basic authentication in Microsoft Expression Web on a computer that is running Windows Vista, you may receive the following error message.

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To work around this issue, follow these steps:

1. Click Start, type regedit in the Start Search box, and then click regedit in the Programs list.
2. Locate and then right-click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WebClient\Parameters
3. Point to New, and then click DWORD (32-bit) Value.
4. In the right pane, type BasicAuthLevel to name the new registry entry, and then press ENTER.
5. On the Edit menu, click Modify.
6. In the Value data box, type 2, and then click OK.
   
   Note The mapping is as follows:
   • 0 - Basic authentication disabled
   • 1 - Basic authentication enabled for Secure Sockets Layer (SSL) shares only
   • 2 or greater - Basic authentication enabled for SSL shares and for non-SSL shares
7. Restart the computer.

Basic authentication is one form of user authentication where a user is identified to the server.

When the server is configured to use Basic authentication, the client computer transmits the users' credentials to the server. If the channel is not encrypted, such as in typical HTTP traffic, a malicious user on another computer on the network can possibly intercept the user name and the password of that user.

By default, Basic authentication is disabled in Windows Vista. When Basic authentication is disabled, either the client computer uses a different authentication method (if the server supports a different authentication method), or the request fails.