XP, need to change Applied Policy

Helping my sister here: her PC was a workstation on a domain. The computer was giver to her and nobody changed it from being a member of the domain to a Workgroup before they gave it to her. There is some sort of GP in effect that won't allow her to install a driver, even when logged in as Administrator. When I run GPRESULT /v it shows, under the "Computer Settings" section, for the line "Group Policy Applied From", something like "bigkahuna". Under the "User Settings" the same line shows "N/A" (which is what I want the "Computer Settings" to show). How do I get rid of the "bigkahuna" policy being applied?

Thank you,
Bill