Looks like the socket for intercommunications between the Xlate engine and the engine got lost. You know its the Xlate engine because the thread reporting it is the Xlate thread xlate_series.
You can run netstat -an | grep 127 and see what the status on that port is or you could simply try to init the ICL database, hcidbinit -i.
As to why it happens. Why does a lot of stuff happen with every OS? It is not necessarily Cloverleaf, it could be the TCP/IP stack or other things. No such thing as a perfect OS or a perfect app.
If it happens frequently, contact Support.
