I would clone the hard disk or replace the hard disk with a backup immediately. Looks like the disk is about to fail, or it too late and has failed already.
EXT4-fs (sda2): warning: maximal mount count reached, running e2fsck
this has been flagged on the Linux file system. Sometimes typical power failures ect.. causes corruption and can be tagged as needing to be checked with e2fsck. But in your case a steady build that is acting "strange" indicates a failing disk. Or corrupt data is being written for other reasons, faulty hardware ; memory ; drive controller.
EDIT: have you ran e2fsck to check the file system?
Code:
sudo tune2fs -c 0 /dev/sda2
Code:
e2fsck -v /dev/sda2
Link here
This should reset the mount count warning. The issue is perhaps you have corrupted data, either from faulty drive or from multiple powerfailures ect without running e2fsck afterwards. (not shutting down completely prior to power off)
my .02
Realtime system did not load
Have you tried to reload linuxcnc after you get his error? Sometimes when I get this error a reload will bring it back up.