Fortran operator priority error for exponent with ifort

I get different behavior between Portland and Intel Fortran compilers when evaluating a simple expression with an exponent followed by multiplication. I am pretty sure that pgf90 (and gfortran) work correctly based on my understanding of operator precedence, but I would like to get a second opinion, as these things can be a little tricky.

Here is my code simplified to a very simple form. When launched using ifort, an expression of the form is d1=a**-2*binterpreted as d1=a**(-2*b)if ifort is equal d1=(a**-2)*bto pgf90 and gfortran. If I remove the negative sign from the exponent, all three compilers interpret this as d1=(a**2)*b. If I change * b to + b, I also get good behavior from all three.

program badvals
  implicit none
  real :: a, b, c1, c2, d1, d2

  a = 2.
  b = 4.

  ! Works with addition following the exponent.
  c1 = a**-2+b
  c2 = a**(-2)+b

  ! Ifort differs with multiplication following negative exponent.
  d1 = a**-2*b
  d2 = a**(-2)*b

  print*, "c1, d1       = ",c1, d1
  print*, "c2, d2       = ",c1, d2
  print*, "c2-c1, d2-d1 = ",c2-c1, d2-d1
end program badvals

!Program output for ifort v13.0.1.117: (either -O0 or -fast):
! c1, d1       =    4.250000      3.9062500E-03
! c2, d2       =    4.250000       1.000000
! c2-c1, d2-d1 =   0.0000000E+00  0.9960938

!Program output for pgf90 v12.10-0: (either -O0 or -fast):
! c1, d1       =     4.250000        1.000000
! c2, d2       =     4.250000        1.000000
! c2-c1, d2-d1 =     0.000000        0.000000

!Program output for gfortran v4.1.2: (either -O0 or -O3):
! c1, d1       =    4.250000       1.000000
! c2, d2       =    4.250000       1.000000
! c2-c1, d2-d1 =    0.000000       0.000000

, ""? Intel?