this problem is not a web browser vulnerability... switch to
linux and you'll never see it again. 
worms other than blaster or sasser may cause "NT authority"
shutdown... cos other viruses can copy the shutdown code.
i once encountered this automatic shutdown when booting my first
mini-PC (on Win2K) for the very first time. scared the hell out of
me until i pulled out the LAN cable and applied all the Win 2K
patches i had.
