Form controls on some pages do not work as expected. This applies to various advanced controls, for example calendar control or parts of HTML Editor.
When web traffic for the page is captured (Fiddler is easiest, Wireshark or Network Monitor work as well), external scripts for these controls are retrieved via ScriptResource.axd which returns HTTP 200 OK but the response content is empty - 0 bytes.
We have seen at least 2 different causes for this symptom: