I tried Scott's suggestions from the Machine-Wide and the Site-Only fixes, which basically updates the browser definition file of the .NET framework, to no effect. The hotfix described in the Microsoft knowledgebase that is supposed to fix this issue also does not work for me.
In the end, I tried forcing the browser to emulate IE9 by sending a meta tag from my page as described here:
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE9">
With .NET websites, inserting this in the Masterpage automatically fixes all pages. IE sucks.