[CentOS] system-config-cluster problem

I have a 2 node cluster that has been running for a year, and is still
up and working fine.  However, a yum update at some point broke
system-config-cluster and it cannot load the management tab anymore,
because it *thinks* the node is not part of a cluster, yet, all of the
definions are there and I can modify them and save, but cannot publish
the changes to the cluster using the tool.  Has anyone else experienced
this problem, or know what may be wrong?