Google quietly announced yesterday on Google+ that they will drop support for all versions of Microsoft Internet Explorer except Internet Explorer 11.
Google said, "starting on March 7th, 2016, AdWords will only support Internet Explorer 11. If you use Internet Explorer 10 to access AdWords, we recommend you upgrade to the latest version of Internet Explorer or any of these supported web browsers."
Why is Google doing this? "we want to provide you with the best AdWords experience possible," Google said and "to do so, we focus on optimizing AdWords for the latest versions of your web browser," they added.
Here is a list of supported browsers if you love IE.
Forum discussion at Google+.