Astra 1.7cdti cambelt problems

[snapsgti]

Hi all
I have a Astra 1.7 cdti on a 06 plate i recently replaced the cam belt and tensioner and roller. All was ok until i went for a drive today and the engine started to make a funny noise lucky i was nearly home. After closer inspection i found that the cam belt has nearly completely shreaded as though the belt has been rubbing on the cover.
I am just wondering if anyone else has come accross this before and can shed some light on what would cause this?
Thanks

[fearless]

Fuel pump pully is known for coming loose on this engine - may be worth checking as it may have thrown the belt off line