A decade-long scheme of systemic fraud by Houston-based Allied Home Mortgage Capital Corp. cost taxpayers $834 million in insurance claims on defaulted loans and forced thousands of the company’s customers to lose their homes through mortgages that were “doomed to fail,” according to a lawsuit filed by a former branch manager of the company and which the U.S. government officially joined yesterday. Allied Home, which is based in offices at 6110 Pinemont Dr. (above) off the Northwest Fwy. not far from Houston’s new FBI HQ, claims to be the largest privately held mortgage company in the country (99 percent of the company is owned by founder Jim Hodge), with 200 branches, down from a high of 600. Separately, the company has now been suspended from issuing any FHA-backed loans or GNMA-backed mortgage securities.