Can't install Adobe AIR on XP

Two days ago, I found that my BBC iPlayer was no longer working. I uninstalled it and tried to install it again, but I was unable to - the installation uses AIR first, and when I looked at the process list, there was an AIR process running several times, obviously not working, I think it tried itself like 8 times. So I then thought okay, I will uninstall AIR and start again. I couldn't even uninstall it normally, I had to use Windows Install Clean Up to get rid of it. Then I downloaded the latest version, tried to install, but the program runs without anything showing on the screen. I see Adobe AIR Installer.exe in the process list but it's doing nothing.

I've tried disabling my antivirus (I use AVG and Advanced System Care) but this hasn't helped.

Why does AIR suddenly hate my pc?