NIS Idle scans and power settings ?

Will the Idle time scans that NIS perform keep a computer from entering standby mode ?

I have my computers power settings set to monitor off 1 hour, hardrive off 2 hours, and standby at 3 hours, but I find that unless I actually put my computer in standby mode manually, the automatic power down does not occur.  So I am assuming that NIS is causing the computer to not power down...is this correct ?    Is there a way to correct this ?

Thanks,

BY