IE7 and Vista Ultimate

I recently upgraded to Windows Vista Ultimate , the problem I am having is that when using IE7 on a couple of websites I am being prompted to ensure cookies are enabled ( They are) and I have placed both sites in the approved list, one of the sites is Amazon.co.uk , it lets me log into my account but will not allow me to do anything in it until I have cookies enabled?? I have checked all privacy setting etc and all appears ok . the other site is my umbrella company Parasol IT which will not let me lo in at all as it thinks cookies are disabled . can any one help ??