Stilly, you were lucky you didn't throw out some ordinary-looking, yet precious object belonging to your son whilst cleaning that room. Very lucky. Note my earlier post at 7:38 PM, which you may have missed.

By the way, I have encountered exactly the same problems with those damn mattress pads. Just as you describe. It took me about 15 very frustrating minutes to get one back on the mattress a couple of weeks ago (after having washed it). I'd get 2 or 3 corners down and...SPROING!!!