ipad 4and ipad 1 problems

My ipad 1 crashes so I want to install a fresh ios 5.1.1. Everytime I try to re-install it gives me a corrupt download message. I've tried wireless and wired.

On my ipad 4 my apps sometimes download and other times fail. I cannot connect to itunes either. I have a macbook pro, virgin 60 meg broadband and airport extreme. Tried on 2.5 and 5ghz mode. Still no joy.

Anyone else getting this?