I am currently having an issue in an application I am working on where I am utilizing MediaElements. The MediaElements are in a RadDocking control. When I switch tabs so the they are not being displayed they are unloaded. I can confirm this because the Unloaded Event is fired. I found a thread where someone was having a similar issue due to virtualization. I have looked through the Docking control though and cant find anywhere that virtualization is turned on.