I have a simple update panel with a button that refreshes a radio button control, I recently noticed a few days now that some of the pages generated by ASP.Net containing my control the trigger does not firing to perform the post back. I have notice this behavior on my cache pages because if I load the same page not cached the update panel works, and to make this even more odd if I kill the cache and re cache the page the update panel works fine, so it seems as if the first cached instance of the page was missing something that enables the update panel to work.