NAS542 accessible through web browser GUI but not through Windows Explorer

SupaCoopa

Hello all.

This problem seems to have appeared since I updated my NAS542 to the latest available firmware, as I used to have access through Windows Explorer (under Network) with no problems.

I can access my NAS through a web browser and I can download and upload files to the NAS via the web GUI.
But none of my computers on my home network can access it through Windows Explorer, under network.
It just... isn't there, as it used to be.
Also the NAS Starter Utility can't find it!

I have to repeat, I had full access through Windows Explorer on all computers, up until recently.

All my computers run on Windows 7, no firewalls of any sort used.
NAS has a static IP, configured via my modem/router.

Thanks in advance.