rattle/screech slipping belt?

[karl210]

Sometimes when i come to a near stop and the dsg stays in 2nd, when i set off and the revs are low and the car struggles a bit i get a screech/rattle noise which sounds a bit like a belt slipping. It does it in first sometimes but mainly when its at very low rpm. Does this sound like a belt or im sure ive heard in the past alternator bearings or something? cheers