changing windows 2003 SBS password, prevents SQL Server2005 to start

We have SQL Server 2005 installed over Windows SBS 2003 Server. SQL Server authentication mode was set to Windows Authentication mode at the time of installation.

Now if we change Windows Administrator’s Password, SQL Server doesn’t start.

We have also tried by changing SQL Server authentication mode to SQL Server and Windows Authentication mode, but it didn’t work.

Any expert advise please ?