IE11 Issues

I have been successfully using CKEditor 4.0 for a while now and recently my company upgraded our browsers to IE11.  I noticed in the CKEditor that I can't highlight/select text to apply a style on previously saved text.  The only way to apply styles now seems to be to select all style options first, then start typing. This doesn't happen in IE10 and less.  I've tried upgrading to CK editor 4.3, 4.4, etc. - nothing seems to fix it.  In fact, now I consistently get a runtime "Unhandled exception at line 715, column 251 in http://localhost:63745/ckeditor/ckeditor.js 0x800a139e - JavaScript runtime error: NotSupportedError"  message in Visual Studio.  Not sure where to go from here...