Smartware Backup renders Notebook unoperable

Notebook (OS Windows 7 up to date with automatic Updates) I have
attached via a Netgear Gbit Router one MyBookLive NAS (purchased some
time ago) and one MyCloud NAS (purchased last year)
WD Smartware Pro (2.4.14) and the Firmwares of the two NAS are updated
to the last available versions.

When I (after a complete factory reset )
configure Smartware to perform Backup of the Sony Notebook onto the
MyBookLive, after some time it renders the Notebook unoperable. The
Machine slows down that eg. shutting down takes 15 to 30 Minutes. The
same is the case with restarting it. Programs start very slowly seem to
freeze every now and then. Something to mention specially is, that
Firefox does not navigate to URLs (neither entered in the navigation bar
nor by klicking on a Link on a WEb-Page that was alredy loades before I
started Smartware Backup even though navigating between browser-tabs
(that have been loaded before starting backup) is responsive and fast. I
am not sure if the Web-Browser-Phenomen occurs immediately after
starting Backup or after some time.

After some time-killing experiments (I had to repeatedly shut down the
Notebook brute force) I found out, that the Notebook is almost very soon
responsive again, as soon as I disconnect it (or the NAS) from the
network cable.

But to get back access to the NAS I have to turn off the Backup in
Smartware. So I have to attach the NAS back to the network, which again
slows down everything almot immediately. With some patience I manage to
start Smartware and to access the page where I can deactivate the
Backup. From this point in time on everything is fine again.

I can copy data to and from every of the both NAS without problems.
The computer works undisturbed and uses both NAS as external storage.
(Public Folders)
BUT as soon as I activate the Backup again, within short, nothing goes

I dont like the Idea to have to look for some commercial products to
perform backup onto my WD-NAS as Smartware - from its featurs - looks
promising. But why does it bring my Notebook to freeze/slow down. And what can I do against it?

Considering this is a very specific issue then perhaps it would be best to contact WD Support about this. You can do so over the phone or via E-mail.