Browser doesn't matter -- it's that some destination sites don't like working inside frames. The vote frame used by the AQ thus gets all wonked out. The danger here is that it usually looks like the destination site fucked something up and the only way to tell, yes, is to try the destination URL outside the voteframe, via copy/paste.
Amusingly, the way in which each such site breaks is different. eBay displays a 'this auction has expired or cannot be found' message which looks so intentional that legions of Alphas have (and continue to be) tricked by it.
Rule of thumb: if you cannot see article content, suspect voteframe shenanigans. Copy/paste the destination URL to check out the article, then use the 'problems' link to vote on it.