NIS 2009 16.2.0.7 is not updated in its proper time

I have a problem with NIS 2009 16.2.0.7 I bought and installed yesterday, consisting of quick updates that do not reach the pace they should. Sometimes half an hour passes without reaching any updates and I have to perform live update manually, then reaching the pulses properly.

-Windows Vista Home Premium sp1

-intel pentium dual core 1.46 GHz, 2gbRAM

-S.O. clean in all its parameters

-no other security program installed.

thanks in advance