Menu item in panel doesn't work. Can't select in "open with..." menu in Nautilus.

I noticed that Gnome-media-player is no longer an option in the "open with..." menu in Nautilus, it has been there in previous versions because it was set as the default on my system.

Further investigation led me to discover the menu item in the panel under Applications | Sound & Video didn't do anything. I suspect these two things are related.

Things I've discovered:
If I open Alacarte, trying to open the properties for the GMP menu item doesn't open the properties dialogue. It does, however, create a file in ~/.local/share/applications called gnome-media-player.desktop.undo-# where # is a number every time the properties button is pressed. These are removed when alacarte is closed. The menu item also refuses to be deleted.

Running alacarte from the terminal produces this output when I click on properties:

(gnome-desktop-item-edit:15576): Gtk-CRITICAL **: gtk_tree_model_get_iter_first: assertion `GTK_IS_TREE_MODEL (tree_model)' failed
**
ERROR:panel-ditem-editor.c:757:panel_ditem_editor_setup_ui: code should not be reached

And this when I press delete:

Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.6/Alacarte/MainWindow.py", line 627, in on_delete_button_clicked
    self.on_edit_delete_activate(None)
  File "/usr/lib/pymodules/python2.6/Alacarte/MainWindow.py", line 333, in on_edit_delete_activate
    self.editor.deleteItem(item)
  File "/usr/lib/pymodules/python2.6/Alacarte/MenuEditor.py", line 352, in deleteItem
    self.__writeItem(item, hidden=True)
  File "/usr/lib/pymodules/python2.6/Alacarte/MenuEditor.py", line 549, in __writeItem
    keyfile = util.DesktopParser(file_path)
  File "/usr/lib/pymodules/python2.6/Alacarte/util.py", line 29, in __init__
    if len(self.read(filename)) == 0:
  File "/usr/lib/python2.6/ConfigParser.py", line 286, in read
    self._read(fp, filename)
  File "/usr/lib/python2.6/ConfigParser.py", line 510, in _read
    raise e
ConfigParser.ParsingError: File contains parsing errors: /usr/share/applications/gnome-media-player.desktop
 [line 14]: 'realvideo;video/x-matroska;video/x-ms-asf;video/x-msvideo;video/x-ms-wmv;video/x-ogm;video/x-theora;\n'

Things I've tried to do:

Purge/reinstall GMP.
Deleted any GMP related entries from ~/.config/menus/applications.menu.
Deleted ~/.config/menus/applications.menu.
Deleted ~/.local/share/applications/gnome-media-player.desktop.

None of the above have fixed the problem.

[EDIT]GMP runs fine from the command line and other launchers such as Gnome-Do.

Ubuntu 10.04
gnome-media-player:
  Installed: 0.1.2-1bzr95~lucid1
  Candidate: 0.1.2-1bzr95~lucid1
  Version table:
 *** 0.1.2-1bzr95~lucid1 0
        500 http://ppa.launchpad.net/gnome-media-player-development/development/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status