This might be not what you are looking for but open 'Control Panel' and on
the left you will see Control Panel Home and beneath that, Classic View.

click on Control Panel Home and then Security and you should see Security
Center.

Norton [symantec] admits that there are issues with their 'protection
center' and the native Vista Security Center.
Do yourself and Vista a favor and get rid of Norton 360 ASAP. Replace it
with a non-destructive, Windows compatible AV ... free AVs include Avast
and AntiVir.
Use the native Vista firewall in conjunction with a hardware firewall
[ like in a router ] and the system will be well protected.

MowGreen  [MVP 2003-2008]
===============
 *-343-*  FDNY
Never Forgotten
===============

Hello Alexander,

Other folks may have additional ideas for you; hope this helps a bit,  take
a look at this

Security Center

<http://www.blackviper.com/WinVista/Services/Security_Center.htm>
Look for Dependencies: What service Security Center needs to function
properly:

Black Viper's Windows Vista SP1 Service Configurations

<http://www.blackviper.com/WinVista/servicecfg.htm>
see if that helps:

Other than that, I'm about out of ideas, so good luck with it.  

Let us know maybe someone else can conjure up something else to try.

Good luck

To Christopher, Mowgreen [MVP], Engel:

Thank you all for the trouble.

To Christopher: no it's not.  All active links to the Security Center page
at the Welcome Center, Control Panel, and at the Help & Supprt Section of
Windows Vista are all visible.  But when I click on them, I only see HDD
activity and then ... nothing.  Since the File System checker reports
everything is ok, I suspect that only my registry may have been corrupted;
all system files may still be intact.  Moreover, the System Restore utility
could not restore my system to restore points before 13May due to a corrupted
registry(?) file that it requires.

To Mowgreen [MVP]:  I have been using Norton 360 v1 since Aug2007 and just
updated to v2 last week.  I never had any problems with it and Windows Vista
until this.  Two virus attacks were blocked by Norton 360 on 12May.  It may
have affected my Norton 360 v2 and Windows Vista SP1 but I only noticed the
problems on 13May, or; the interaction between Windows Vista and Norton 360
v2 while responding to the attack may have been the cause.  At any rate,
Symantec suggested that I re-install v2, and I have.  Everything is working
fine now, except of course, I cannot access the Security Center although I
can access and make changes to the individual components at the Control Panel.

Meanwhile, Microsoft Tech Support has not responded yet.

To Engel: thanks for the lead.  I have taken a gander at www.blackviper.com.
Some pretty powerful stuff there and may be way over my head, but I will
pursue that channel if Microsoft Tech Support cannot help.