Our product build machine is running Windows XP.  On September 1st we ran Windows update which installed 28 updates (we were a bit behind) on that machine.  From that point forward builds on that machine no longer run on Windows Vista machines. KB970653, KB970653, KB970653, KB890830, KB890830, KB973540, KB973354, KB973507, KB973507, KB973869, KB971633, KB971633, KB951847, ...