Vista - Internet Explorer Cerificate Problem

Hi

I have recently changed to Vista and have an annoying problem. My homepage
is set to http://uk.msn.com/ I know this is the genuine address and had no
problems in XP. Now whenever I start Internet Explorer the page about a
problem with the websites security certificate pops up like this

The security certificate presented by this website was not issued by a
trusted certificate authority.

Security certificate problems may indicate an attempt to fool you or
intercept any data you send to the server.
We recommend that you close this webpage and do not continue to this
website.
Click here to close this webpage.
Continue to this website (not recommended).
More information


a.. If you arrived at this page by clicking a link, check the website
address in the address bar to be sure that it is the address you were
expecting.
a.. When going to a website with an address such as
https://example.com, try adding the 'www' to the address,
https://www.example.com.
a.. If you choose to ignore this error and continue, do not enter
private information into the website.

For more information, see "Certificate Errors" in Internet Explorer
Help.



Now I know there was a couple of dodgy Microsoft certificates in the
past and these are in the Untrusted Publishers Tab in the Internet Options.
So how did these get there and how can I either delete these safely or get
an updated Microsoft Certificate to allow me access to the homepage without
having to click on

Continue to this website (not recommended).

Thanks.


Ian