continuous rebooting after windows update

yesterday evening windows reminded me to update my windows XP professional.
some security updates have been installed. after that i restarted my system
- and now: nothing works anymore! my pc starts normal but few seconds after
the windows XP logo appears the system shuts down and reboots automaticly. on
and on and on...strange thing is that the windows logo seems to be a
different one after this update - normally the addition "home" or
"professional" is seen in the logo or?! now there is nothing like that.
nor safe mode is working, neither booting from the CD ROM.
i use windows XP professional with SP1+2.

any suggestions? thanks in advance!

regards
daniel

grrrrrr, this ****ing mircosoft windows sytstem. once again i regret that i
use this ****. how can it happen, that microsoft advices me to update my
system and after that nothing works anymore? and in this forum no microsoft
supporter is able to answer such a question??? unbelievable! this software
costs so much money - pure robbery!

without regards
daniel