I was following the NIS 21.1.0.18 thread because I have a similar issue on my PC (see highlighted BUp3 below). I didn't think anything about it until I started reading through the noted thread.
I have an AMD dual core processor with 4g Ram running XP Pro SP3. Over the years by religiously controlling systray items and removing as much of the original HP crapware as possible I managed to get my boot up times from 6 minutes down to about 3.
I say about 3 because the PC does not boot up the same way each time.
I experience 3 types of boot ups:
BUp1 - fast (2.5 min) - 1 scnd black screen with startup options, flash of windows logo bluescreen then grey screen for over 2 minutes then desktop pops up with systray and associated items including NIS, and I'm good to go.
BUp2 - normal (3.0 minutes) - 5 scnd black screen + options, 30 scnd blue logo screen, then desktop appears with taskbar and empty systray and systray icons gradually appear over the next 2.5 minutes with Norton showing up last (green checked).
BUp3 - slow (3.5 minutes) - 10 scnd black screen + options, no blue logo screen, instant desktop without task bar lasts about a minute and then task bar shows up, then 30 scnds later Systray appears with Norton in systray redflagged, other items eventually load and then Norton flag turns green.
Note: Enable boot time protection is set to "Aggressive". Which must have been the default because I'm not a sophisticated user and have only recently started looking at settings in conjunction with an recent thread I started.
Comments appreciated, thanks Dave