mt machine simply freezed and after hardware reboot I got this msg:
[…]
Starting services…
Fatal internal error occurred!
Please reinstall the router.
Shutting down…
[…]
I thought the problem was in HDD, so I simply changed it, installed mt on the new one and recovered backup config on it. (and the router is working fine now)
But today I tested the old disk and it is working… So maybe the problem was somewhere else…
any ideas?
reinstalling on the same disk will most probably fix the problem, if there is any. maybe you got some bad sectors on some important part of the disk
yup, just formatted and reinstalled mt on that disk and it works fine in a test machine(at least for now). But still, I’ll leave the new disk in my router 
It is highly recommended to use good quality hardware for an important piece of hardware as a router. We always suggest to use new and professional grade drives. You can keep the other machine for testing.