Hiya Andre,
It's very important to remove any old *.pyc files you have. When the
.py files are removed, volatility finds the .pyc file and attempts to
load it as a module. Since we removed the Windows 2008 vtypes (because
they were identical to the Vista vtypes), that might have caused your
error. Please remove all *.pyc files, and let us know whether that
solved your problem or not...
Mike