Having updated Windows 8 I have found it to be the worst OS to date. All of the event logs are the same, yet the PC hangs where you can do nothing but do a hard reboot. Go to the event viewer and shows the hang log, but can not find any problems when you try to go and search for it on Microsofts site.
I’m still waiting to hear back on the Nvidia issue but I suggest that the next step for you is sorting out (i.e. turning off) what doesn’t need to be started during boot.
Press [windows key] + [x] and select Task manager, then pick the “startup” tab to see what is trying to load at the boot… anti-virus aside you can shave considerable time off the average 8 boot time from this screen without buggering your system.
p.s. Feel free to post a screen of the list if you don’t understand what any of the programs do.