Asterisk process stop responding to CLI interface and to new calls

Last weekend I updated a lot of RPMs on the FreePBX distro. After this big update, I'm experiencing, two or three time in a day, a strange behavior: Asterisk stops to respond to its CLI and no new calls can be instantiated. I must connect via SSH to my FreePBX virtual server and must issue a couple of 'fwconsole restart' commands to restart Asterisk (the first indicate that Asterisk can't be stopped) and return to normality. I already checked a lot of things in the critical moments but without fortune: the resource available to the server (CPU is below 40%, memory is below 60%, swap is below 5%), the alarms from the VMware ESX where the server is virtualized (none present), the status of Asterisk process (top reports Asterisk below 2% of CPU), the full log (I found no evidence of the cause of this issue).