Vista - slow shutdown & pwr on disables NIS 2004

Sorry, if I'm posting in wrong section. Really need help. I have Dell 2400
Series, Wndws XP2, cable modem, and have been experiencing above problems
since yesterday. Prior to that (for one week), was only able to access
internet (IE7) via system restore and safe mode. Discovered Symantec
automated troubleshooter yesterday which suggested I cut off its firewall. I
did that and internet access was made possible, but now shutdown is very slow
and NIS disabled at power on.
(I've been trying to post at NIS forum, but email confirmation link to
verify my resgistration (to my gmail account) was unlinkable. And someone
suggested that Wndws startup may be causing NIS disable. (BTW, uninstalled
WinDfndr and keep getting a "failed to initialize app" msg.) Also ran event
viewer and found PerfNet error, MS Installer failed to connect to server,
etc. Somebody Pls help!!

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thanku,sher