Hi Paul and Matt, I had a comprehensive suggestion from Tech Support as follows:
Remove the Linkstation from the network, press the reset button at the back for 15 seconds and then release, wait 2 minutes and then power it down. While powered down, connect it via ethernet to the network port of your PC.
On the PC, go to start, control panel, network connections and then right click on your LAN conection and selec properties, double click on the internet protocol TCP/IP and select "Use the following IP address" and set the following details
IP Address: 192.168.11.100
Subnet mask: 255.255.255.0
The Default Gateway and DNS entries can be left empty and then click ok and then ok/close your LAN connection properties and your control panel and wait 1 minute for the IP settings to be saved by Windows.
Power on the Linkstation and wait 2 minutes, disable all firewall and anti-virus software and check if you can connect to your shares and GUI also try reaching it from the Nas Navigator.
If you can then you should now be able to re-attach it to the network and also access the unit
Please check the Buffalo web site www.buffalotech.com (select eruope) and ensure you are running the latest firmware for your Linkstation
END
Unfortunately, this did not work at all. There is something really odd about this. My wife's computer that also backed up to this drive via the network also cannot connect. The common denominator (bearing in mind that the router is not the issue here) is MS Windows SP3.
As I am unable to perform a firmware update that might solve the problem, the unit is effectively dead. I can still access it through my Archos 705 though (wireless).
I have just had a thought though - I can try connecting my work lapttop directly to the drive. Can one of you confirm the IP address to use - 192.168.11.10 as in this thread or 192.168.11.100 as per the Buffalo tech guy?
Thanks for everyone's support so far. I'm learning loads from you. Hopefully, I will have a successful conclusion.