Updated Vista to SP2, and can't boot up.

I have been running Vista on Service Pack 1 for some time, and tonight I tried
for the second time to install Windows Vista Service Pack 2 for x64 systems
(KB948465).

Both times I was told it downloaded successfully, when shutting down I was
told it installed successfully. Then Vista gets halfway through booting up
and a blue screen error flashes up lightning fast (too quick to read) and it
restarts over in a never ending loop, getting only as far as the blue screen
flash every time.

I can successfully restore back with recovery to the point before the update
was installed, but if this continues, I will never be able to update!

Any Ideas? Before recovery I tried the repair options, but it could not find
anything wrong. Now the update log reads "Installation status: failed, Error
details: Code 800F0816"

My specs are Dell Studio XPS 435MT, i7 CPU, 6Gb RAM, Windows Vista Home
Premium, SP1.

Free unlimited installation and compatibility support is available forWindows

Free unlimited installation and compatibility support is available for
Windows Vista, but only for Service Pack 2 (SP2). This support, originally
scheduled to end 26 November 2009, has been extended until 26 February 2010
so get a move on! Availability of chat or e-mail support differs depending
on your geographic location. Some issues may require more advanced support
for which there is a charge.  Go to
http://support.microsoft.com/oas/default.aspx?prid=13014&gprid=582034 &
select appropriate category (i.e., Download issue; Installation issue;
Issues after you install a service pack).

Vista SP2 Installation Tips:

??? Your computer will restart several times during the installation process:
Make certain you have saved your work and closed all open applications before
beginning the install.

??? Disable (1) your anti-virus application, (2) any real-time system
protections afforded by any anti-spyware applications (except Defender), &
(3) your third-party firewall (if any) and then (4) enable the Windows
Firewall _before installing or uninstalling_ Vista SP2.

??? The installation process can take an hour or much longer, depending on
server demand.  If you are installing SP2 on a portable computer, make sure
that you plug-in the power cord and have the battery inserted into its bay.

??? Vista SP1 is a prerequisite for installing SP2. If you use Windows Update
or the Automatic Update feature in Windows Vista, you will not be offered
the option to install SP2 until you first install SP1.
--
~Robear Dyer (PA Bear)
MS MVP-IE, Mail, Security, Windows Client - since 2002
www.banthecheck.com