Event ID 1123 and Event ID 1122 (node lost communication with cluster)

Hi everybody!
I need some help on how to correct getting Event ID 1123 and Event ID 1122 on one of two cluster nodes every hour. This is a two node cluster running Windows Server 2003 EE SP1 (NovaScale 3045 Itanium2 )

In the event wiever every hour on one of two cluster nodes I receive such Warnings:
a)Event ID – 1123. The node lost communication with cluster node 'Cluster0' on network 'Heartbeat Cluster Connection'.
b) Event ID – 1123. The node lost communication with cluster node ' Cluster0' on network 'Public Network Connection'.

How to eliminate this problem? Any suggestions?