I had a similar problem to this a few weeks ago.
I reinstalled Windows XP (no service packs included), then downloaded SP3 and it was fine.
Then I downloaded the next lot of updates, including IE&, and got the same problem as you.
I seem to remember on the Windows update page there was a place that showed the error number.
I did a search on that and found a "fix" which solved the problems and allowed me to download all the fixes successfully.
Hunt round the Windows Update page and see if you can find the error number.