This is fresh install of Windows XP Home (version including SP2) on a
slower machine (800 MHZ VIA, to be used as a print/file server).
Machine has full internet access via a NAT box.
Windows Update (or Microsoft Update, either has the same symptoms) gets
to the page where one choses express or custom. Pressing either causes
"svchost" to start using nearly 100 percent of the CPU, with IE taking
the remainder (to draw the endlessly-moving green bar?). The machine is
essentially unusable; other programs and services won't start (actually
they do start but it takes minutes or 10s of minutes) If I leave it for
a long time (hours?) a failure message eventually pops up. The only
other cure seems to be a power-off/on reboot.
Same thing happens shortly after startup if automatic updating is
enabled. (so automatic updating is disabled.)