Fortran divide check crashes interactive '386

[Robert Lupton the Good]

A colleague has a 386 running Interactive's unix, and the LPI fortran
compiler. He reported that a divide by zero in fortran crashes the
system, so I wrote a trivial C programme to catch SIGFPE --- it works
fine. So I wrote a stub to set the handler from fortran, and now it
works fine ONCE --- if you run the fortran a second time it still
crashes the system. 

I have no further ideas --- do any of you?

				Robert