This is a Visual Studio 2003 error that i have received.
To fix this...
1. In the Internet Explorer, select the "Tools" Menu, then select "Internet Options".
2. Select the "Security" Tab in the new window.
3. Select the "Internet" globe icon.
4. Click the "Custom Level..." button at the bottom.
5. Locate the "User Authentication" section (it is at the bottom in IE7).
6. Select "Automatic logon with current username and password".
7. Click "Ok" twice to complete.