How to troubleshoot Network Authentication in Win XP SP3

When connecting to a Windows 7 using remote desktop connection from a Windows XP client running service pack 3 or earlier, you get the following error message: ”The remote computer requires Network Level Authentication, which your computer does not support”. (NLA)

To resolve this problem you need to know a bit of knowledge of registry editing.
To enable NLA in XP machines; first make sure you got Windows XP SP3 installed. It is also recommended to make a backup of your registry before you continue.

Please note:

“Just in case if you get in trouble start windows in safe mode (F8) and use  the Last Known Good Configuration feature in Windows XP. Also make sure  that you enable  system restore  this is very important!”

To configure Network Level Authentication please follow the steps below:

1. Click Start, click Run, type regedit, and then press ENTER.
2. In the navigation pane, locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
3. In the details pane, right-click Security Packages, and then click Modify.
4. In the Value data box, type tspkg. Leave any data that is specific to other SSPs, and then click OK.
5. In the navigation pane, locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders
6. In the details pane, right-click SecurityProviders, and then click Modify.
7. In the Value data box, type credssp.dll. Leave any data that is specific to other SSPs, and then click OK.
8. Exit Registry Editor.
9. Restart the computer.