Random Power Shutdowns: NUC RoonOS

Random Power Shutdowns:

NUC7i5BNH 16MB RAM 256GB Intel PCIe NVMe 500GB SSD

RoonOS 1.0 (build 159). Local 500GB SSD hold the music library.

After buying Roon Lifetime the following now happens - Roon randomly shuts down (Trial version worked fine).

The following message appears just before shutdowns:

{ umount: can't unmount /roon/app: devices or resources busy

umount: can't unmount /roon/data: devices or resources busy

the system is going down now

Sent SIGTERM to all processes

mDMSResponder:mDMSResponder (Engineering build ) (Sept 21 2018 14:28:52) stopoing

Sent SIGKILL to all processes

Requesting system power off }

I have reinstalled RoonOS, changed the DIMMS and the 256GB PCIe.

Any help? Many thanks