PGP Desktop 10.1 shuts down with no functionality available or tray icon visible, if the "PGP" program group folder is removed from the "All Programs" Windows XP menu (for example by relocating it to a submenu of "All Programs"). When it's restarted (from a relocated shortcut pointing to PGP Desktop or by rebooting the machine), it will attempt to reinstall, launching the installer. The installer prompts for "PGPDesktop.msi", which at this time is usually removed from the folder under the temp path ([User]/Local Settings/Temp). Allowing this "reinstall" to finish will restore functionality, but also force the creation of a new copy of the program group in "All Programs". This behavior is repeatable.
 

Because the installer doesn't even provide options to select placement of shortcuts in the "All Programs" menu and moving the shortcuts folder completely disables the entire application, this is a major problem for machines with custom Windows shortcut menu structures.