My neighbor's computer running xp hangs for 20+ seconds when IE8 is first opened. After that, multiple openings of Explorer causes no delays. Her computer is running NIS 2012- with latest updates - which was upgraded from NIS 2011. First opening of explorer you get a blank page with the upper left message - connecting. There it hangs until you see the Norton tool bar pop into view. From there, the home page immediately follows. I finally disabled the Norton tool bar and the page opens normally at startup. I don't know why it would only do this when first opening IE and not any subsequent openings.
I might add I've done the full system scans and used Malwarebytes (free version) to look for problems. Malwarebytes found two programs - Adware.MyWebsearch and PUP.FunWebProducts - had been making mischief on her computer and removed them. (Why not Norton?)
I was/am planning on returning her computer to NIS 2011 after my own problems with IE hanging after the 2012 update. I returned my XP computer to NIS 2011 and haven't had a hangup or ID safe problem since. I mention all this since it seems to resemble the OP's experience. Any suggestions or ideas are appreciated.
I do have the logs for the problems found by Malwarebytes and would gladly share them with Symantec if it would help.