The IMF is just another name on the list of crash predictors. A few years ago when house prices shot up there was much talk that the crash was coming. Some homeowners thought it best to sell at the top, rent until after the crash, then buy low. It was a bad move as prices kept rising. All you can do is listen to the experts and decide what it all means to you.
I may end up eating my words in my 40% reduced house. Maybe some are relying on this crash to get on the ladder. Fine. For them. I have 2 sons renting well over the age I was when I first shackled myself with a mortgage. But a rush of buyers suddenly affording a place will create new price rises and off we go again.
As for Northern Rock. Greed. Running out of funds for lending would, in the past, result in a famine. My first mortgage was with the local council, who, along with many councils, lent mortgage funds for a while in the 70's. Abbey National, who we saved with for2 years, ran out of funds, declining a mortgage on a 10k house.
Now its different. Savers can't keep lenders going and they borrow to provide substantial mortgages. As this cheap money started to get expensive, and the US sub prime problem started, Northern Rock were in trouble. Statistically their lending over the last year was so high that some bankers (and the Bank of England) worried they were handling too much borrowing. No questions were raised and it ended in the run.
Lenders are now more cautious who they lend to, how much and if the borrower can afford it. No one wants to be the next Northern Rock.
That's a good thing. Can it be good to over borrow because lenders let you, then worry about how to meet the monthly payments? Misery made more miserable if you end up with huge payments on a property that just lost value.