We have over 20 CCR's in production.
The only one that locked up was acting as an NTP Server.
All other CCR's are NTP clients that sync with our Cisco Core/Edge router.
We are testing 5.23rc1For everyone with this problem. Try latest 5.23rc1 with fix
http://www.mikrotik.com/download/share/ ... .23rc1.zip
Shields? Can you give more info?