All computers can access NAS, NAS can't access anything.

mdgm & sphardy - many thanks for your inputs... at least I can now feel slightly less alone in my explorations. They should get human beings like yourselves to write a manual.

The Windows Firewall is completely off on this XP-SP3 machine, and as for 'pushing' backups from clients rather than getting the ReadyNAS to 'pull' them... my wife and son wanted me to organize backups for their computers which wouldn't require them to do anything. I had the - perhaps rather foolish - idea, encouraged by the vendor, that the ReadyNAS Duo, once set up, would periodically scan the network for incremental backups on the home network computers, leaving us all free from worry about dying hard disks and loss of data (happened twice in the last 5 years), and free of the further cost and complication of client software on each machine to 'push' backups. I basically want to save all relevant data on all home machines on the ReadyNAS, and different OSs store relevant data in lots of different places, so I thought incremental backup of the root directories would save everything 'just in case' - and OK, the NAS will then be backing up changes to the registry, temporary folders and so on, but that shouldn't be a huge strain once the initial root backup is completed, the data might even come in handy after a disk failure.... and I get the impression that a lot of people who buy the 'home' versions like the ReadyNAS Duo are looking for pretty much what I'm looking for (incremental disk-image backup would be even better... but I also get the impression that Netgear is basically making servers for professionals to install, and don't really understand their 'low-end' domestic customers... even those who started programming on a PDP-12 forty years ago, and have wasted too much of their lives editing printer kerning tables, modem queries &c, in the slightly less distant past).

I've already tried nearly all the combinations you guys suggest (BTW, is 'Browse' always greyed-out and non-functional as on my computer and your image? Wouldn't surprise me...). I haven't edited the registry to reset encryption levels, but I'm trying initially to get the backup function to work on this XP computer. I can't (well, easily) believe you need to edit the registry to get the late-2010 ReadyNAS firmware/software to work with the most common and seasoned OS out there...

One little point (since when I have more energy again for this I might try a more specific test backup from some small share on this machine again) - do you in fact need a full UNIX path, or is //COMPUTERNAME/SHARENAME(/SUBFOLDER) enough (as a newbie I'd expect to find this basic question answered in the online manual, the software Help or the Community FAQs, but again, like other frustrated posters, I clearly misunderstood the intended market/public for this sort of baby NAS)?

And if computers aren't in fact password-protected (I trust my wife and son, and it's a hassle waiting for the login prompt, then waiting agian for the full bootup), do you still need to fill in the login details in Frontview (all the other computers, and the NAS shares, can be accessed by Explorer/Finder without login over the network).

PS: As I asked initially, could this scenario possibly correspond to a corrupted RAIDiator, or a component failure in the NAS?