trust relationship between this workstation and the primary domain failed

Hi there,

Does any body knows on how to fix The trust relationship between this workstation and the primary domain failed.Our network is windows server 2008 r2 , and affected windows computer is windows 7. i had tried to login as administrator account but it wont work. i unplug the lan cable and login as local administrator it wont work, is there any other method to fix this problem?

thanks