Back in March I wrote about three updates that caused my Aero transparency effects to go bad but also caused my others browsers to slow to a crawl. At the time I mentioned IE10 was one of the possible culprits but I made a statement that it probably wasn't to blame. Yesterday, IE 10 appeared to gain elevation in the hierarchy of updates and was the sole item at the top of the update list. It seemed like a good opportunity to exonerate IE10.
Guess what? Turns out IE10 was guilty. I didn't bother doing all the same tests to see if it slows down all the other browsers (you don't think they would do that on purpose do you?). I just noticed the aero transparency effects were gone. Again doing a system restore failed, so either system restore is broken on my machine, or what seems more likely to me is that IE10 has managed to break much more than just aero. I tried uninstalling IE10 but Aero transparency was still broken.
Getting Aero back
Luckily, by this time I have seen more reports about this problem than when I first reported it a couple of months ago. In particular, one site indicated that while installing IE10 causes the problem, restoring Aero required uninstalling a different update: KB2670838.
Use the Program and Features control panel and select the View installed updates. If your system is like mine you then get to search through 400+ updates and find KB2670838. Use the uninstall button at the top to remove it. While there I would suggest you also remove IE10.
Now I just have to keep a watchful eye out for both IE10 and this KB update to make sure they don't try and reinstall themselves. There are also other reports that much more than Aero gets broken and one interpretation that Microsoft did this on purpose to enable some Win8 functionality on Win7. Gee thanks.