Here's a strange problem. I have an active directory domain controller running Windows Server 2003 at home. I am dual booting Windows XP and Windows 7 on my desktop PC. I joined Windows 7 to the domain without problems, but when I log off and try to log back on to the domain using my username and password, I get a 'username or password incorrect' error. If I type my domain credentials as: email@example.com I can log on to the domain. Then I log off and the same error appears. So, I use the following logon: home\username and can log on to the domain again. Then I log off and the same error appears. I use this: firstname.lastname@example.org and log on to the domain again. I can never log on to the domain the same way twice. I have no problems logging on as the domain administrator and have no problems logging on to the domain using Windows XP. Strange. Any suggestions would be appreciated.