An existing server did not respond to an NFS mount request, so after retrying a number of times (default 1000), the mount(1M) command has ceased. Nonexistent servers or bad mount points produce different messages.
If the RPC: Program not registered message precedes this one, the requested mount server probably did not share (export) any file systems, so it has no NFS daemons running. Have the superuser on the mount server run share(1M) on the file system, then run /etc/init.d/nfs.server start to begin NFS service.
If the requested mount server is down or slow to respond, check whether the machine needs repair or rebooting.