Is fix for 818173 present in win-xp sp2?

Our environment consists of clients on win-xp sp2 with
server on win 2k3.

Intermittently InitializeSecurityContext() is throwing up
SEC_E_NO_CREDENTIALS.Going through I found
that we are hitting the issue reported in

The article pertaining to this do not mention clearly whether this
issued is fixed in sp2 for XP or not.

Can you please clarify as to in which SP the fix for
the issue reported in 818173 has gone in XP, 2K and 2K3.

If the fix is already there in win-xp sp2 then are we hitting
another bug?