My PC config:
Host OS - Windows 7 32-bit Guest OS - Windows XP SP3
When I enable the integration features (in the settings dialog), check the "enable at start up" option, on start up I'm asked the password with which I'll be logged in. When I enter the password a message appears:
"The system could not log you on.Make sure your user name and domain are correct, than type your password again..."
BUT: when I disable the integration features, I can log on successfully(no password is asked).