XP SP2 and scf /scannow

[wrench45us]

ongoing adventure

with a fresh install of XP
and install of SP2

i though i had everything reacquainted/re-installed to the new OS, when I couldn't get my e-mail working.

i called my isp support and he had me run scf /scannow
and that had me reinsert the initial XP CD that shipped with my system.
and then everything appears to work
i was worried it was overwriting SP2 files with the original XP files, but my system still seems to think SP2 is installed

http://www.updatexp.com/scannow-sfc.html

from what i gather from this article, some cache was still corrupted after a fresh install

i'm wondering how that's possible after a fresh re-install? given the problems i've been having with my system i was beginning to suspect it was going south. all appears to be stable now, but id don't understand why i needed to do this scf after a fresh install?