Sorry my advice didn't work. You should be able to do this, since you were able to do it before. Techs and JDC071391 both have good ideas;...
Take a look at this link: http://www.microsoft.com/windowsxp/using/setup/learnmore/tips/knox2.mspx This procedure should let you logon...
Rebecca, I'm guessing you have Windows XP. Try clicking on Start, All Programs, Accessories, Command Prompt Cliff
Separate names with a comma.