406 1.9td Aux belt issues

[caveman_si]

Started doing an oil change and flush just after lunch today and its all gone very very wrong. Well not the oil change not even I could mess that up.

Droped the old oil put in the flushing stuff as per instructions. Got out my cleaning stuff to clean the insides and startered her up.
After about 5 mins of running she started sounding funny like all clatterty and thumpy for a second and then it went quiet and then it happened again. Images of things going badly wrong flashed through my mind so i dived through the car (I was in the boot) and turned it off.

Lifting the bonet I was faced with an aux belt that some how had jummped and started to shred itself!
Happy I am not but I am pleased its nothing else.
The cambelt is fine and as far as i can tell everything else is too. Except the aircon pump as its got shreded belt around it but theat should be find once cleared.

So auxbelts any hints and tips or does the haynes cover it in enough detail??

So much for Exam revision for monday