Hi Tom.
The only machine that runs the new EXE and SP6 DLLS is the machine that 'installed' the service pack.
When our new exe and dlls are moved to any other machine that ran the SP5 version of our EXE, the message comes up when we try to launch.
So, that it why I think there is an operating system file that is being updated by the SP6 install; we would need to include that OS file with any updates sent to our customers. (>It sounds like you have missing or obsolete file(s). -> I agree, and I'd like to know which DLL/OCX/etc really needs to be distributed.)

GorgAnna