While attempting to diagnose a problem of not being able to get a
successful installation of iTunes 8.0 on my Dell C521 running Vista I
did the following.

At the suggestion of an iTunes forum member that I check for malware I
downloaded and ran Spybot. I also ran the online Kaspersky scanner.
Neither showed any problems.

Following a procedure suggested in the forum (http://support.apple.com/
kb/HT1926)
I ran the Windows Installer Cleanup utility and removed iTunes and
Quicktime in their entirety. I had previously used this utility
with no problems.

When I tried to reinstall iTunes I got a message that Windows
Installer Service could not be accessed and that it was not installed
correctly.

I tried to download a new version of the installer but now I can’t get
online because my wireless adaptor is no longer detected.

I also get a message that the Windows Security Center Service is
turned off yet when I try to turn it on it says it can’t be started.
I also notice that my log list of installed updates now shows there
are no updates installed on this computer. (it was fully up to date).

I attempted to backtrack using Restore but it too is inaccessible with
the message “The Volumne Shadow Copy service used by System Restore
is not working”. At this point I can’t get online to download any
fixes or contact any help center.

So what was the inconvenient loss of iTunes has degraded to the
situation I have now. What has happened? I’m lucky I have my old
laptop to have some semblance of operation.