When you change you Systemadminstrator password you have to change any asscociated services passwords. TO do so -
- Go to start>run
- type %systemroot%\system32\services.msc and press enter.
- click the column titled 'Logon As'
- right click on each serivce where Systemadminstrator is set for credentials and select properties.
- On the logon on tab change the password to the new password.
- Restart all affected services.
Be sure to change the Systemadminstrator user account to password does not change.
If you have code which has the password hard coded or connection strings in your web.config this could also affect the account status.