Multicast data issues

I have three x4150 machines that we use to run a web site in a JBoss
container as well as a few other java applications.  These systems are
all running Solaris 10 x86 with the latest patches.  We also run TIBCO
RVD version 8.22 on each of the global zones.  The web application and
the other java apps run within their own zones on the physical hosts.
We've had an issue several times recently where the RV data ceases to
flow to one or more of these machines.  The only way we've discovered
to restore multicast service to these hosts is to fail over from the
primary to the secondary NIC (they're running IPMP), or to reboot the
system.  Has anyone else experienced anything similar?  I have an SR
open with Oracle, but so far they have not provided any interesting
insights.  Any help is greatly appreciated.