broken Make on PI

[John D. McCalpin]

I have a medium-sized, moderately complex Makefile that I use to
maintain my current modelling project.  This Makefile seems to generate
the correct behavior on a variety of machines, including:
	IRIS 3000, VAX VMS, ETA-10 UNIX (Sys V), Sun 4

I get the following broken behavior on the Personal IRIS:

	1. I update a header file
	2. I type 'make model'
	   It 'makes' correctly
	4. I type 'make model' again
	   It repeats the previous make, even though everything
		is up-to-date.
	5. I repeat step 4 several times.
	    Usually by the 3rd or fourth time, it finally understands
		that everything is up-to-date and it does not
		have to make anything anymore.

I have checked the times on the files, and they are correct.
I have tried 'make -t' and it doesn't seem to notice --- it still
re-makes the target several times more than it needs to....

The only thing that I am doing which is unusual is that I have turned
off most of the rules and replaced them with my own, since I am using
a fortran pre-processor that make does not know about by default.

Any ideas out there?
--
John D. McCalpin - mccalpin at masig1.ocean.fsu.edu - mccalpin at nu.cs.fsu.edu
		   mccalpin at delocn.udel.edu