Eng 1 bleed air inop and closed (non etops MEL), crossbleed open. A faulty fan air thermostat then caused excessive temperature in bleed 2 and the valve closed.
Several requests to descend, pan pan, finally crew declared an emergency and descended.
http://www.sust.admin.ch/pdfs/AV-berichte/2257_e.pdf
there's an AIB report dated 9 Nov 2001 about A320 G-MEDA which suffered a dual bleed fault due to thermostat failure (by design, if I may add). French DGAC published a recommendation 31 October 2001. Airbus subsequently addressed the issue with Service Bulletin No. A320-36-1061 - which had not yet been carried out on the Swiss aircraft (2001 -> 2013!).
Nothing happened. Yet when I see all the known holes lined up for this kind of incident to happen again, I do wonder "what if there had been one more hole", and I do wonder about the ability to learn fast enough from past incidents.