Update to my original thread, because I've found a workaround for the problem I described a few messages earlier.
I've got an actual DG834v3 that I wanted to recover with the utility, and it failed in exactly the same way as described earlier.
Googling for the problem led me to a Netgear forum where various solutions were presented - one of which was that the software needs 2 network adaptors to be present. As I had a spare one lying around, I went with that. The spare adaptor happened to be a Netgear gigabit PCI.
With the 2nd network adaptor installed and running, the modem in recovery mode and connected to said Netgear adaptor, I ran the recovery utility, which allowed me to choose the Netgear network adaptor, and the display was no longer corrupted - it showed me the MAC address etc, and allowed me to flash the modem, which took a few minutes and a flurry of LED activity.
It's all working fine again now!
So, for anyone coming here having problems with the DG834 recovery utility from Netgear, the solution is one of these :
o Have 2 network adaptors, connect the dead modem directly to the 2nd one
o Have 2 network adaptors, one of which must be a Netgear one, connect dead modem directly to this one.
o Perhaps the utility only works with a Netgear adaptor.
I've no idea which of those statements is 100% accurate, but the
second one worked for me!
Ian