parallel issues

I'm running archlinux and I've manually compiled DOLFIN using dorsal-0.8.2.
I've included the following packages: parmetis, cgal, swig, armadillo, mtl, scotch, trilinos, fiat, ferari, ufc, ufl, ffc, viper, instant, petsc, slepc and dolfin. I have MPICH2 installed.

The serial versions of all the demos run fine, and as for parallel, the linear problems also work (e.g. poisson).
However, when I try to run the Cahn-Hilliard demo, I get the following error:

% mpirun -np 2 ./demo_cahn-hilliard
Process 0: Number of global vertices: 9409
Process 0: Number of global cells: 18432
Process 0: Partitioned mesh, edge cut is 112.Process 1: Partitioned mesh, edge cut is 112.

[0]PETSC ERROR: [1]PETSC ERROR: --------------------- Error Message ------------------------------------
[1]PETSC ERROR: Arguments are incompatible!
[1]PETSC ERROR: Incompatible vector local lengths!
[1]PETSC ERROR: ------------------------------------------------------------------------
[1]PETSC ERROR: Petsc Release Version 3.1.0, Patch 7, Thu Mar 17 13:37:48 CDT 2011
[1]PETSC ERROR: See docs/changes/index.html for recent updates.
[1]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
[1]PETSC ERROR: See docs/index.html for manual pages.
[1]PETSC ERROR: ------------------------------------------------------------------------
[1]PETSC ERROR: ./demo_cahn-hilliard on a linux-gnu named #### by #### Wed Jun 22 16:23:24 2011
[1]PETSC ERROR: Libraries linked from /home/####/Work/FEniCS/lib
[1]PETSC ERROR: Configure run at Wed Jun 22 15:54:34 2011
[1]PETSC ERROR: Configure options COPTFLAGS=-O2 --with-debugging=0 --with-shared=1 --with-clanguage=cxx --with-parmetis=1 --with-parmetis-dir=/home/####/Work/FEniCS --download-umfpack=1 --download-hypre=1 --download-mumps=1 --download-scalapack=1 --download-blacs=1 --download-pastix=1 --download-scotch=1 --prefix=/home/####/Work/FEniCS
[1]PETSC ERROR: ------------------------------------------------------------------------
[1]PETSC ERROR: VecAXPY() line 559 in src/vec/vec/interface/rvector.c
--------------------- Error Message ------------------------------------
etc...

Is this demo missing support for newer versions of PETSC?
The DOLFIN installation on my ubuntu machine (taken from the fenics PPA) ran this demo perfectly, but I noticed it was using petsc-3.0.0. Or perhaps there were some errors in linking the libraries...
(I would just like to know if this is a known issue.) Thank you in advance for your help.