A real estate investor in Flagler Beach, Florida didn’t know a computer problem at Fifth Third Bank had dumped bad information on his credit file, sending his credit score into the basement, causing him to lose deals because he couldn’t get financing, and causing his line of credit with another bank to be cut off. (See “Real-estate investor sues Fifth Third Bank over computer error”)

The problem, which Fifth Third says occurred when it was consolidating with another bank, was not disclosed to customers unless they complained—and most didn’t complain until they applied for a loan and were turned down.

Real estate investing can be a fast-moving business. While it’s possible to delay closings while problems are worked out, not every deal will wait. That’s why it’s important to keep an eye on what’s going on in every aspect of your financial life—especially in your credit file.