Android market issue?

well i just purchased a sony ericsson xperia 8 and when i go on android market on it and when i try and download an app it says " starting download" but it wont install the app at all it doesnt say anything in the notification bar that i've downloaded one or nothing i've tried resetting the phone that hasnt worked, and also resetting my router which hasnt worked either so does anyone know what the problem is and how can i fix it ? thanks