Lesson: Know what you're getting into. Falling prices, rising foreclosures, new construction grinding to a halt -- that's nothing compared with the housing problems Tom Hanks and Shelley Long experience in "The Money Pit."

From the moment they move into their Long Island fixer-upper, things go south. The front door falls off, the stairway collapses, the wiring in the kitchen explodes, and holes in the floor swallow both the bathtub and our hero. Yet the pair stick it out. Buying a house -- at all costs -- is a deeply embedded part of the American dream. (See "The 3 worst reasons to buy a home.")

Now we know adjustable mortgage rates, unexpected home repairs and plunging values can quickly turn that dream into a nightmare. According to a 2009 study by Zillow, more than 20% of homeowners are "underwater," meaning they owe more on their mortgages than their homes are worth. And a survey by Demos, a nonpartisan public-policy research and advocacy organization, indicated that 38% of U.S. households are in debt because of home repairs.

The lesson in all this? Don't buy a house without knowing what you're getting into. Start with "Your 5-minute guide to homebuying."

Continued: "Sunshine Cleaning"