One poster who had sought to buy a condominium was turned down by a national lender, despite an acknowledgment by the bank that "all of the accounts have a zero balance, are in good standing, and show no other derogatory information." After spending "hours on the phone with the creditors and credit bureaus trying to resolve this issue," nothing was resolved, said the poster.

Christopher Cruise, a Maryland-based mortgage originator and a founding member of the National Association of Responsible Loan Officers, said "there's no question -- when there are lots of other applications and business is good," applications requiring extra time and hands-on research "just aren't going to move."

Evan Hendricks, author of the book "Credit Scores and Credit Reports," and publisher of Privacy Times, a newsletter that outlined Fannie Mae's policy in a recent report, calls it "extremely unfair to honest consumers who are simply doing what they should -- challenging misinformation." Instead, he said, "they get ambushed" when they apply for a mortgage.

Freddie Mac's policy on disputed tradelines is broadly similar to Fannie Mae's, according to spokesman Brad German. Though the specific requirements of its automated system are "proprietary," he said in an e-mail, "the presence of disputed tradelines will affect (the system's) determination of a borrower's credit reputation and its decision to accept the application or refer it to the lender for manual underwriting."

Why are both Fannie and Freddie so uptight about applications with disputed accounts? Mainly because during the past several years, credit repair companies have been gaming automated systems tied to credit scores by disputing accurate, but negative, items. When tradelines in a consumer's files contain a "disputed" notation, most scoring software ignores them for the purposes of computing the score.

A seriously delinquent account that could legitimately depress a FICO score might be taken out of the equation -- at least temporarily -- if a "consumer disputed" notation was in the file. Fannie and Freddie are trying to protect themselves from gamesters and frauds.

But what about the impact on disputed items where the consumer was right -- or files where creditors failed to remove the disputed account designation? For the time being, it's tough luck for all applicants with disputes in their credit files.

Fannie Mae, however, says it is "reviewing" its policy, so maybe there's a chance for a change.