ReadyNas 6.2 (NAS locks up entirely)

I have two identical ReadyNAS 104 boxes (though purchased at separate times ... clue?). Newer one purchased April 2014. Old is at 'head office', new at 'remote location'. Both were stable initially (6.1.7, 6.1.9). I upgraded both to 6.2.0 in the failed hope of better features/user interface, and ever since have had terrible instability issues on the 'remote' unit - but not the 'head office' unit. I upgraded to 6.2.2 in the hope of remedies, but no luck. Unit locks up within 24 hours, hard power unplug/replug required to recover. Nothing is going on with the remote unit (it's not being used in any way); the backup process I had has been abandoned, so all I do right now is hand-carry a USB drive between locations and then copy files from the USB to the remote NAS.

I have just upgraded to 6.2.3-T1721 in the hope of some stability.

I ordered a replacement earlier this week, thinking I may have a dud unit, but now seeing all the posts here on the forum I see this is a common problem. I'm tempted to return it unopened. IF support are willing to work with me on this (I'm an IT guy) I may consider keeping the new unit and even shipping the failing unit back to NetGear for analysis.

From the file 'initrd.log':
[2014/04/29 16:35:25] Updated from ReadyNASOS 6.1.7 (1396977042) to 6.1.7 (1396977042).
[2014/11/16 11:52:23] Updated from ReadyNASOS 6.1.7 (1396977042) to 6.1.9 (1409791183).
[2014/12/02 16:35:09] Updated from ReadyNASOS 6.1.9 () to 6.2.0 (ReadyNASOS).
[2014/12/26 16:35:04] Updated from ReadyNASOS 6.2.0 (ReadyNASOS) to 6.2.2 (ReadyNASOS).
[2015/03/26 14:25:26] Updated from ReadyNASOS 6.2.2 (ReadyNASOS) to 6.2.3-T1721 (ReadyNASOS).