Problem sorted

(I think)
Looks like it was zone alarm that was blocking the site.Strangely enough I`d gone into the privacy tab and selected "allow" for all cookies,mobile code,web bugs and private headers for this site but still wasn`t having any success it was only when I turned on privacy advisor and clicked "click here for details" it was coming up with site name as uk.yahoo.com. I had cookie control set to allow session and persistent cookies but 3rd party was blocked, once I`d changed this to allow-hey presto logs me into all pages on the site no probs.
Just hope this doesn`t compromise my security at all