IE 11 / Win 7 error

Hi all, I’ve encountered an error message (attached) in the latest build of IE 11 on Windows 7 with the following page:

I also receive the same error message on other pages with the latest version of Cesium, but only in IE11.

On some PCs with this configuration (IE 11 / Win 7) the Error construction CesiumWidget message appears, but on other systems it does not.

Any tips on configuring Cesium pages to work with IE 11? Having the latest graphics drivers and IE11 build doesn’t seem to fix the problem.