Vista login problem

Hi all,

 

I need some experts advice on how to fix my vista log in problem.  I've changed my company's laptop membership from a domain to a workgroup and restart the computer and cannot log on with my previous user name and password.  I am also not able to change the user name.  I traced my problem to windows support: http://support.microsoft.com/kb/317049/en-us , but no real solutions.

 

My laptop is Ispiron 1420 with Windows Vista Business.