I'm not sure what you mean when you say you've tried manually, but sometimes when all else fails you can download the SP3 file first and then install it. Here's the link
http://search.microsoft.com/en-us/DownloadResults.aspx?q=xp%20sp3%20download
I have been trying to install XP service pack 3, now, for 2 days with no success. The error is always the catalog thing. I have done the following;
done a clean boot
renamed catroot2 folder
manually (as per instructions)
this involved a lot of program registrations, etc.
with Microsoft's fixit thing
It runs right up to the end and then gives me the error message and rolls stuff back. I have no idea what I might be doing wrong.
Thoughts?

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