BTDT. Macrium Reflect Image on a 2.1TB EHD fixed all files and OS to the new 500GB hard drive.
A week ago tomorrow MicroSlime had their Toosdee update....and had three for XP (still covered on 64 bit and "Enterprise" systems)...and the update overwrote AV files, locked the computer up (wife's..only one with Updates still internally enabled), and took 5+ hours to figure it out...and I did. SafeMode worked.
fltmgr.sys was the alleged culprit, but came down to msconfig and disabling everything but Windoze components, then unloading AV and re-load, and it works fine...and updates are now killed.
We used to have to watch those updates with MS like a hawk..."custom", write the KB numbers down, search all of them, find out which ones were threaded up, load the good ones and wait for the next week and do it again.
Couldn't trust them then, don't trust them now.