When you right-click on a file and choose Open-with, none of the applications may be listed in the menu. Also, the
Choose Program... option may be missing, and the Open With entry is repeated again.
I found that the Live Mesh shell extensions 'WLCShellMenuHandler Class' was causing the problem by using ShellExView from
http://www.nirsoft.net/utils/shexview.html. I went through each context menu extension disabling/enabling until I found that my Open With context menu worked correctly after disabling the Live Mesh extension 'WLCShellMenuHandler Class'.