Pulling My Hair Out

Lately I have been dealing with my computer. I downloaded a virus last week that would not let me go to Windows Update. I went through all the motions of scanning and deleting but every time I could not update. I formatted the hard drive and reinstalled windows. After getting some updates the rest would not install. I couldn’t figure what went wrong so I reinstalled again and downloaded updates in groups to see if one messed it up. I got every update and XP works fine for now.