Yep, same on a couple of 2k3 x64 boxes last night.
This is known issue affecting all IE+ x64/ia64 systems. A revision to those 
packages is forthcoming, possibly later today.
-- 
Lawrence Garvin, M.S., MCITP:EA, MCDBA
Principal/CTO, Onsite Technology Solutions, Houston, Texas
Microsoft MVP - Software Distribution (2005-2009)
MS WSUS Website: http://www.microsoft.com/wsus
My MVP Profile: http://mvp.support.microsoft.com/profile/Lawrence.Garvin
Wow! What an ingenious idea, MS is ticked off with the slow uptake of
Windows Vista so they decide to make XP even more annoying with
incessant prompts. But clearly MS wants to beta-test the concept first
with the smaller 64-bit Windows user base first...pure genius!
(Disclaimer: The above is deemed as sarcastic humor, and should be
interpreted as such...so laughter is optional)