I am using a RB750GL and a hAP lite both running on v6.33.3 stable. Both are used as PPPoE router and are interconnected thru EOIP / IPSEC.
When changing a comment on a firewall rule in WinBox suddenly all interfaces dissapear except the ether-interfaces, cpu goes up to 100%. Surprisingly the connection keeps up for a while even when connected over one of the dissapeared interfaces. So I do a reboot and everything is fine again as long as I do not change comments in firewall rules...
