>Have the runtime files also been updated between VFP9sp2.exe and VFP9_sp2.exe? There is no change to the version number.

Yes they were. They have the same version as new VFP9.exe - 9.0.00.5815. You have to uninstall and reinstall VFP9 in order to properly apply new SP2 (VFP9_sp2.exe).