I had the same problem earlier this week: IE didn't show any flash, FireFox did it correctly.
Since I also own MM Studio MX, MX2004 and Studio 8 FlashPlayer was already installed.
I solved the problem by putting my firewall offline and downloaded the same flashplayer version two times. The first time nothing happened however I could see 'flash installed' on adobe.com. The second time I saw the charts again.