Did your friend try the instructions recently put up on the USCIS case status Web site?:
"If you were granted permanent resident status or entered the U.S. with an immigrant visa more than 60 days ago and have not received your first permanent resident card, please call 1-800-375-5283"
Be persistent on this number, they may need to call it more than once until getting put through to an officer who can help/initiate an enquiry.