I did doublecheck this for you, and I forgot to let you know.
Unfortunatly, that's a problem with WoWHead. It does the same thing at
http://www.wowhead.com/talent/include/example1.html (wowhead's public demo)
So, it seems that their only options are to run Firefox, or upgrade to IE7.
Sorry I don't have a better answer, I don't know if they've ALWAYS had it broken like this for IE, I thought it used to work, but I could very well be mistaken.
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It's all in the reflexes.