Hi Bruce,

> Is there a way to step through with the debugger to see if and where the preprocessor is reading these files from?

Yes, put the following into each include file:

#IF MESSAGEBOX("This is file whatever") == 0
#ENDIF

You get a messagebox every time VFP uses this include file for compilation. If you use VCXes, be prepared for lots of messagesbox, though. Alternatively, you could use STRTOFILE() to produce a log file.