A user is always asked for user id & password on every login for the Home screen so that the system could display the Role Center screen. And if the user skips the step (escape) then the error message displayed is:
|An error has occurred. Contact your administrator for further assistance.|
Normal 0 false false false EN-US X-NONE X-NONE Refresh Role Center | Close Role Center
This has recently been started ever since the Enterprise Portal configuration wizard was reconfigured by one of the administrators.