I found an entry in the registry where it stores all the start menu orders and I found that deleting that folder tree in the registry caused all the start menu items and sub menu items to sort alphabetically and when new things were installed they were added alphabetically to the list instead of being added at the bottom of the list.
The list stayed sorted until I dragged something by mistake and the registry key was recreated and everything was given an id of where it was
I found this key by searching the registry for start menu or a name of a program on the start menu
You would have to open everyone's registry seperatly to do it for everyone but you could do it to the default user's registry so all new users would get an auto sorting start menu
If you can't find the key in the registry tell me and I will have a look
