Nonsense with Mopac!

This is a relatively large molecule of 27 atoms. The Mopac7 dat file, below left, has been used, with either a AM1 or PM3 hamiltonian. The flat starting structure of 4'-Hydroxy-4-Azobenzenecarboxylate(-), the anion of a simple azodye with one hydroxyl group and a deprotonated carboxylgroup at the other end, is given in the top drawing. After optimization, which converged, the left products are formed: a non flat molecule, which has lost its carboxyl group as a CO2 molecule, one of the benzene rings reduced to a 5-ring and the azogroup forced into a 3-ring with the extraannular C-atom. The same starting structure gives a perfectly behaved optimized structure with Gaussian03W rhf/sto-3g (to mimic the meagre basis set of Mopac7), and in a Mopac type calculation under Gaussian with AM1, the correct result is obtained, too.
With the neutral molecule, the carboxyl-protonated species of 28 atoms, Mopac7 again is not able to produce a reasonable optimization result. This time the carboxyl group stays, but the azogroup is forced into a 4-ring with the nearest C-C edge, and the second benzene ring is pyramidally bound to one of the N atoms, see below right from Molden! G03W/PM3 or AM1 gives the correct structure, again.
AM1 VECTORS DENSITY PL CHARGE=-1 PRECISE XYZ
4'-Hydroxy-4-Azobenzenecarboxylate(-); 
ES 27.11.2003; add EXCITED for S0-->S1
C  -2.353689  1 -2.988919  1  0.000000 0
C  -0.956657  1 -3.027300  1  0.000000 0
C  -0.195639  1 -1.875220  1  0.000000 0
C  -0.829467  1 -0.630280  1  0.000000 0
C  -2.223494  1 -0.569890  1  0.000000 0
C  -2.966142  1 -1.735427  1  0.000000 0
C   1.799525  1  1.865096  1  0.000000 0
C   3.195668  1  1.865751  1  0.000000 0
C   3.904353  1  3.050585  1  0.000000 0
C   3.220139  1  4.266970  1  0.000000 0
C   1.826928  1  4.275030  1  0.000000 0
C   1.124625  1  3.083292  1  0.000000 0
N   1.144846  1  0.541653  1  0.000000 0
N  -0.129721  1  0.656748  1  0.000000 0
C  -3.239693  1 -4.365793  1  0.000000 0
O  -4.481394  1 -4.165866  1  0.000000 0
O  -2.543773  1 -5.413293  1  0.000000 0
O   3.983027  1  5.437784  1  0.000000 0
H  -0.478811  1 -3.999544  1  0.000000 0
H   0.886102  1 -1.916029  1  0.000000 0
H  -2.701746  1  0.402261  1  0.000000 0
H  -4.048622  1 -1.699312  1  0.000000 0
H   3.716546  1  0.916022  1  0.000000 0
H   4.985558  1  3.054999  1  0.000000 0
H   1.298378  1  5.219419  1  0.000000 0
H   0.041975  1  3.084123  1  0.000000 0
H   3.323379  1  6.174440  1  0.000000 0