When using IE8 and Mendix 3.1.1 I am having problems with buttons and pop-ups: HttpException(413,FULL head,null) - null - null 404 - file not found for file: vtibin/owssvr.dll Could not find mime type for file 'cltreq.asp' 404 - file not found for file: MSOffice/cltreq.asp There are no problems with Firefox. I am using Mendix without an IIS