intelligent updater and NORTON 2009 Problem

Hi

i`m using NIS 2009 and using Dial up to conncet to Internet. it`s hard for me to download every day Virus Defenition so i`m usingintelligent updater. after using this package when i run the liveupdate manually it said i must download about 3 mb , after this when i run it again it said i must download 35 mb.  WHY ? i didn`t have this problem in NIS 2008.

i try in windows xp x86 , Windows vista x86 , Windows vista x64. they have same problem.

 

please help me 

( Note that i have NIS 16.1.0.33 , i had this problem in 16.0.0.25 too )