If you see this error message when attempting to load one of the Shadow Health DCE assignments, the browser you are using is not able to load WebGL - the plugin used to run the assignments. This error message is provided by WebGL, so you may see this in any browser, including Firefox.
The most common cause for the browser not being able to load WebGL is a built in "crash guard" that will block unstable plugins if the browser detects a crash. These crashes can be caused by the graphics drivers, or shutting down the browser, or computer, improperly.
This crash guard is present in both Google Chrome and Firefox