Finally i have reproduced the problem playing with the energy power feature of the nodes where Jboss is installed. I one node go to down with the energy feature and the nertwork card go to poweroff, after that, the power on reported the problem.
I have resolved the problem upgrading Jgroups to 2.6.15.GA, so i have one doubt:
Do you know somebody used Jboss5.1.0.GA with Jgroups 2.6.15.GA?
Thanks a lot!