NVME goes odd line

[Dave_Davis]

When I boot my newly built Ubuntu Machine TB my 2TB NVME mounts and works just fine. A couple of days ago I copied 500MB of data to it with no problem.

However, it periodically "drops out" for no reason I can figure and won't allow me to mount it without restarting the computer.

After a restart all of the files are in place and seem to be error free.

I have tried this with the NVME installed on the motherboard and with it connected with external USB.

The drive was partitioned and formatted (ext4) on this machine.

The common denomiinator seems to be the drive except for the fact that a reboot always restores it.

Any ideas?

Thanks,
-dmd-