Thanks for all the advice !
When in safe mode, i was able to uninstall symantec endpoint protection (it doesn't appear in the list of installed programs) and am able to reboot normally again!
About the drivers
I can guess some, like asio is for my m-audio soundcard delta66 but it hasn't any updated drivers.
But the others i wouldn't really know... teefer??
@jonathan: do i still need the removal tool?
I am already happy that i can start windows normally again