domain name change

Hello everyone,

I have a problem with a pc as, for some reason, in “Network and Sharing Center –> Active Networks” the name of my domain network changed. My domain name is “whatever.local” and this pc is automatically changing to “whatever.local 2”. The user can still use the pc normally, but a problem the he has is that when he opens the outlook, windows keep asking for user credentials and sometimes the account is locked. The windows version is 7 Professional.

Does someone knows why is this happening?

Thanks a lot in advance