renault megane scenic 98?

Hi i have a '98 1.6e Renault Megane Scenic the problem is that sometimes when I pull away I get a vibration and graunching noise,other times I don't.
The vibrating wears off after a short time but it's a bit worrying;I'll have a look @ the driveshafts 2 morro,but any other ideas would be helpful thanx.