(debtor defaulted on bank loan and had CODI to extent forgiven debt exceeded value of mortgaged property; bank issued Form 1099-C to debtor and IRS; lender then sought to collect difference between amount due and value of mortgaged property against debtor (who was in bankruptcy); court determined that filing of Form 1099-C did not bar collection of difference in value between amount due and value of property; Form 1099-C is not admission by creditor that debt had been discharged; IRS regulations on matter not entitled to Chevron deference).