I am experiencing this in 6.7 on one particular router running as an x86 VM. I was able to see the route cache completely full and networking shut down. Since it was a VM, I was able to reboot it and resolve the issue. It does happen regularly with this router. Other than a scheduled reboot, are there other workarounds?
See this thread: http://forum.mikrotik.com/t/problem-with-mount-point/94/1
It suggests the issue is fixed in 6.5, but I don’t think it is. It is still evident in 6.7.