this is from a www.dslreports.com forum. Many are having
the problem and the 'hosts' file edit only works for some
systems (fixed my win2K but not win98 machine)

"If you tried to install the updates after the msblast
worm started some providers have changed DNS information
and the updates will not load. So you may have to wait
until worm attack is over with or DNS changed. MS is also
changing some DNS settings."

Some on that forum also suggest a program called bind-PE
which promises fool-proof DNS, but I haven't tried it. For
win2k and up only, not 95 or 98.

Can download it / get info at http://ntcanuck.com/