Yep. Had the sale of my property fall through twice already. Once because someone changed his mind after about a month of agreeing a sale and the second time because the buyers mortgage fell through (he had a mortgage in principal but the lender suddenly changed their mind on the amount of deposit required).
Being in a chain is just too stressful. Next time I do this, I'll sell up before even looking at other properties. If I have to rent to bridge a gap, I will.