Ted Allrich is the founder of The Online Investor and author of Comfort Zone Investing: Build Wealth And Sleep Well At Night. In this weekly column, he offers advice to investors who are just getting started.

Subprime loans have been in the headlines, not in a good way. Lenders have lost billions. Homeowners have lost homes. It's a real big problem. But for the lenders the problems may only be starting.

While subprime loans are defaulting, there are loans that weren't subprime when they were made and have been paying regularly. But that may change due to their structure. These loans were made at interest rates below the current market rate, called teaser rates. These teaser rates were written for a year or two or even longer. Once those teaser rates expire, the loan then adjusts upward to current interest rates for home loans.

When the new rates adjust higher, so do the payments. Some homeowners won't be able to afford the new payment schedule. The actual number of those is unknown until the end of each month, when the payments are due and aren't made. While interest rates are moving downward at the moment, they may not move down far enough to help these borrowers. That means more mortgages may default over the next several months or years as the teaser rates become current. Only time will tell how many that will be. Not even the lenders know how bad this problem is since there's no way to estimate how many borrowers will stop paying.