If you have an embedded flash in a node the drop down admin_menu's lay under the flash and you are not able to select the menu items.
Repro:
1. Create a dummy node with a YouTube video in the content.
2. Scroll the video next/below the menu
3. Open the menu
Comments
Comment #1
sunMarking as duplicate of #195386: Menu under flash content . Please search for existing issues before submitting a new one.
Also documented in the README.txt.