The menu items will display in alphabetical order UNLESS an application has been installed which turns off this feature. To turn it back on:
Hive: HKEY_CURRENT_USER
Key: Software\Microsoft\Windows\CurrentVersion\Explorer\MenuOrder\Start Menu\Menu
Name: Order
Type: REG_BINARY
Delete the Order key and new items added will display in alphabetical order. You may have to reorder existing items.