I run windows 7 sp1 pro with Norton Security, and all updates, and I have Windows 7 ESU (Extended Security Update) option active.
Everything was running fine until after either Windows 7 ESU security roll up for May 2021 or Windows 7 ESU security roll up for June 2021, or it might have been Norton Security updates during that time.
Started to have 3 minute delays during startup (bootup), then after living with that, and searching logs, started to have long waits and startup errors in Windows 7 log. Then had security not initializing, and other log errors.
Tried many things, many hours/days, and just before giving up, I remembered that I have always (even on my Windows XP machines) - Norton boot time protection option AGGRESSIVE. Changed it to NORMAL and all runs fine.
Seems that Norton AGGRESSIVE hooking of Windows 7 pro SP1 is no longer correct after ESU updates at this level are applied, and causes wait, error, hangs, at startup (bootup). I had been afraid that since my security fixes are still being shipped by Microsoft this might not be tested by Norton people.
(Or for all I know, Norton doesn't work on any Windows 7 with AGGRESSIVE option at this level (time).)