Here's the scenario. Weak home sales and continuing foreclosures result in climbing real estate inventory. This has two effects. First, it makes new homes even less attractive which further reduces construction jobs. Second, it puts downward pressure on home prices, which makes it harder for struggling homeowners to sell their home to avoid foreclosure and also keeps strategic default rates high, exacerbating the problem. Lower home values encourage Americans to save more and spend less, since their wealth is effectively reduced. The Dow drops and credit markets tighten even further, suffocating private investment just as homeowners bunker down and slash spending. Growth turns negative.

2. You Break the Economy

You, the American consumer, are reloading savings after a debt-fueled decade. But as any general will tell you, when an entire squad reloads at once, it leaves everybody vulnerable. It's the same with the economy.

Here's the scenario. Consumer sentiment continues to fall slowly, and spending turns negative again. Small businesses hold off to replenish their inventories or add new workers. Wages and hours freeze, and unemployment takes a leap toward 10 percent in October. Congress is paralyzed, because it's only weeks away from the mid-terms. The stock market sees business revenue trending flat, joblessness rising and Congress doing nothing, and it sparks a 300-point sell-off. Americans frightful for their savings cut back spending even more the next month, and overall growth turns negative.

3. Toxic Assets Return

If you closely followed the bank bailout, then you know it wasn't originally billed as simply throwing money at the banks. Instead, the Treasury intended to purchase the toxic assets from banks, which were the source of investors' uncertainty concerning bank stability. But the Treasury couldn't figure out a way to do this quickly enough to make it effective. As a result, the banks were largely stuck with these bad assets. We just don't know how bad, yet.

Here's the scenario. The residential real estate market's problems continue. Even once foreclosures begin to decline, we see waves of defaults, as modification program participants re-default at rates of 30% to 50%. Commercial mortgage-backed securities continue to deteriorate, as some businesses struggle with weak consumer demand. Home and commercial real estate values keep declining, and so do the value of the assets that back them. Banks with exposure to these toxic securities see another round of losses, and investors question their stability. The market plummets, credit freezes, and growth turns negative.

4. Europe Falls Apart

Europe seems to have avoided an all-out collapse of confidence in its ability to pay back its debt. But things can change, and fast fast. Indeed, the Greek debt crisis went from ignorable wire stories to front page news in a matter of days.