Problems can occur when you are trying to re-install Windows SharePoint Services. The problem occurred when I was trying to install the Dutch version off WSS after I uninstalled the English version.
The Installation of WSS went ok, but when I tried to configure WSS it did not worked correctly.
After some searching I found out that WSS installs his own SQL Server instance but does not uninstall the instance when you remove WSS.
But how do you remove this instance? You cannot uninstall this instance with the normal tools of SQL Server 2005 so you have to do this another way.
1) Using regedit to locate the following registry key:
2) Under this registry key search for “Embedded”. On the left side of the screen, click the GUID that is found with the search. Copy the value under the key named: “UninstallString”.
3) Go to the command prompt and then paste the string. Now, write the following after the string and press enter:
4) An Uninstall program will start.
Know you have uninstalled the instance and you can safely install your version off WSS.