Well, there is always a risk that the real estate market is going to go down and leave you with a mortgage for more than the price of your house. In the past, however, the general trend for real estate is to stop going up in value durring slow periods for the economy. The market moves much slower and with much more hesitation than the stock market.
Tony can probably lend some insight into what banks go through to make sure you will be able to afford your house payment. They may make it nearly impossible to get loans at times, they do like to make sure you'll have the ability to pay them back.
Matthew