I'm having this issue too. I tried the Spore news story, must've logged in 3-5 times then came here. Then I went back to the story and I was able to make a comment.
Now I'm having the problem on http://www.gamespot.com/news/6195969.html?tag=latestheadlines;title;1 and I've tried the same trick above and I still can't rate or make a comment.
I also have the problem on the page above also. Basically, it's ANY article on the site that I'm having problems "logging in" to post comments. Once again, my RSS/news feed is logged in along with my HD downloads, but I can't post comments at all.