The odds are steep, but turn that around, most of the worlds 200+ million XP PC's have no problem with the update, what are the odds of one person having three machines that all have a problem? It is most likely some program that you installed on all three machines that corrupted something in the Windows files. Occam's razor cuts both ways! That is why a repair install could fix the problem on all three machines.

Many, if not most, computers that have those damnable worthless recovery disks also have the windows installation files tucked away somewhere on the hard drive.