When fmt:formatDate tag is used in jsp-page content-language header is added. This is ok, but when formatDate tag is called multiple times, multiple content-language headers are added. This causes that some browsers (including IE) will not display the page. The problem seems to be in SetLocaleSupport.getFormattingLocale which for some reason calls setResponseLocale method and this sets content-language header. This is tested with 1.0.3 and 1.0.5 versions.
*** This bug has been marked as a duplicate of 28248 ***