The trouble is figuring out who holds the old loan.

After issuing mortgages to homeowners, banks routinely sell the IOUs to other banks or institutions such as Fannie Mae and Freddie Mac. Huge volumes of mortgages have been packaged into securities and sold on Wall Street.

Unbeknown to the borrower, the note can change hands again and again - at least electronically - while the bank that issued the loan continues to collect the monthly payments on behalf of the new owner.