Hijack by user "nobody"

I have a My Book World Edition, which has been working fine until recently.  Now when I try to modify a file on the drive, I get a message saying permission is needed from Unix user “nobody.”  And I can’t log into the configuratiton area of the drive.  My administrator’s login name and password aren’t recognized.

Anybody know what is going on?


P.S.  The is happening on only one of two computers I have.  Both run Windows 7 64 bit.  I can use the My Book normally on the other computer.