Unable to boot computer after update

Sony Computer - Started 2 days ago - run a program that
is completely internal to the computer - received XP
update while on line. Now the computer will not boot and
gives a message that either new hardware (none installed)
or a recent upgrade has caused a problem - will not boot
in safe mode (3 versions) or automatically start windows.
When authomaticly start windows is selected, the
Microsoft XP logo shows up then the screen goes blank and
nothing can be done on the computer. I am able to get to
dos prompts by using the restore CD that came with the
computer - but unable to install XP again or do anything
that seems to correct the problem.
Anybody have any ideas?
Gary