I have just had a reply from RealPlayer saying the following...
Good news - we recently released an updated (Universal Binary) version of
the RealPlayer with native support for the new MacIntels.
You can either download this updated version from
http://www.real.com/mac
or, alternatively, from within the RealPlayer itself: under the "RealPlayer"
menu, select "Check for Update".
I, like you have been unable to use RealPlayer with my MacBook Pro but as from this evening everything is working 100% as it should !