If you get this error, than you have a problem with your python-multiprocessing package. There are two possibile ways to solve this problem. You can install the backport or you can patch the latest version of python-multiprocessing. Ive done last thing, so here we go:

// first remove the old version from your debian system
# apt-get remove python-multiprocessing

// get the latest version from svn
# svn checkout http://python-multiprocessing.googlecode.com/svn/trunk python-multiprocessing

// get the patch http://code.google.com/p/python-multiprocessing/issues/detail?id=18
# cd python-multiprocessing
# patch -p1 < 0002-Fix-logging-of-processName.patch

// install it
# python setup.py install

Now this should solve your problems. I hope that the guys behind python-multiprocessing will release soon a newer version of their package.