I did an uninstall and tried again, same problem. Cleaned up another time and even tried a different SID and system ID, exactly the same problem.
I need to apologise at this stage if I've mislead you into thinking this was an install on Red Hat (as per my earlier comments) - what I meant was that it's not SuSe (in terms of a SAP Note that was suggested), and it was BASED on Red Hat - I'm actually running CentOS.... yes I know SAP do not support CentOs, but to all extents and purposes it's the same thing as RHEL, just missing some packages - which I believe I now have. I don't believe that the errors I'm getting are related to this... but perhaps they are? Perhaps there's something missing?
P.S. Note that this is only a test system and not Production, so support from SAP isn't required