"Error 18456" error message when you specify configuration database settings on the Da

I am runnning the Setup program to install Microsoft Windows SharePoint Services. After the Setup program is completed successfully, I configure Windows SharePoint Services settings in SharePoint Central Administration. I then specify configuration database settings on the Set Configuration Database Server page of SharePoint Central Administration, and then you clickOK. Then, you receive one of the following error messages:
"Error 18456" error message when you specify configuration database settings on the Set Configuration Database Server page of SharePoint Central Administrator"

I have gone through the article onhttp://support.microsoft.com/?kbid=889646&FR=1 but it does not help me out. Please let me know if some one came across this problem & i could solve it with your support
Thanks in advance
Regards