In my case I am using the below code,  when ever the reRender called it will not be refreshed. First time it displays fine. But when reRender called the images are not getting refreshed accordingly... I think in IE and FF the cacheable="false" is not working fine as expected. It is caching the images and not allowing to call the createContent action... But Crome its working fine.

<a4j:mediaOutput element="img" cacheable="false" session="false"

                        createContent="#{releaseDetailChartBean.generateEfficiencyChart}"

                        mimeType="image/jpeg" style="align: center; text-align:center;" />

Any idea how to solve this??????