I don't use win7 but on IE8 there are several settings to try depending on what is set now.
In internet options under tools.
You have a few tabs to select.
one is security
Select the trusted sites option.
Then select the sites button
Deselect the Requires server verification checkbox
Add your sties full url. http://www.msn.com
If that is still a problem you can change the security settings for trusted sites on the same page.
Next or other option to try is the privacy option tab.
This is where the cookies are monitored.
you have two choices to check
Sites and advanced.
Advanced will allow you to overide all cookie/ session settings by allowing first party third party cookies and session cookies.
allow all three options
So you may want to try this method as a test only to see if that resolves the problem.
If it does disable it. I would not think they would want to allow any site. and go to the sites button add the url to the site and select allow.
Other than that firefox.
There are to many security items to deal with on win7 then add in ie8.
I hope that was clear as mud