I have removed copystart.exe from the MiKTeX 2.6 distribution.

copystart.exe was used in MiKTeX 2.5 to start the update wizard. In MiKTeX 2.6, copystart.exe has been replaced with copystart_admin.exe, because under Windows Vista the update wizard should run in admin mode. In other words: if, for some reason, you make use of copystart.exe, then you should now use copystart_admin.exe instead.