Hi All
Its amazing, the Amiga has been around so long that someone somewhere will have had the same problem as you, no matter how strange! LOL
Anyway, I am having the exact same issue as the OP here and Im stuck as to what it could be. Heres the rundown:
Hardware spec:
Amiga 4000 Desktop (rev B motherboard I think)
68040 CPU (standard Commodore board that came with the Amiga 4000) rev 3.1
Socketed Buster 11
2MB Chip 16MB Fast
DCE Cybervision 64/3D MK2
IDE hard drive (I think its the original one Commodore installed)
Optical drive (on the IDE bus, its a Lite-On CDRW)
Kickstart 3.0
Workbench 3.0
Nothing additional attached externally or internally.
What Ive done:
I installed the CV64/3D (with great difficulty I might add) into the bottom Z3 slot. There was a network card installed in the top slot at this point (Its a LANrover card).
I installed the software onto WB as per the instructions (via the 2 disks that came with it, labelled as V3 of the software). All went OK and I rebooted. I got the same error the first guy got (exactly the same at the same time).
Troubleshooting Ive done:
Reinstalled WB from scratch, no patches or additions at all - no effect
Reinstalled the software (Cybergraphics) several times over - same issue every time.
Installed Picasso96 on a clean WB install - the board is not seen in P96Mode (I think thats what it is called??) and running the monitor driver doesnt bring up any screenmodes.
Checked Early Startup Menu, the board is identified everytime and shown working.
Changed Z3 slots - no effect
Installed CGX3 on clean install WB - no effect
Downloaded CGX3 and installed on clean install WB - no effect
Removed network card - no effect.
Im stuck as to what to do

Ive only got KS 3.1 to try and Ive noticed a "map ROM" jumper on the CPU card that I might try and disable.
Ive got an A2000 Im waiting for a 3.1 ROM to be delivered for that Im going to try the card in too to make sure the card is OK but the guy I got it off (on eBay) said it was working, he has good feedback so Ive no reason to question him

It was packed VERY well so I cant see it being damaged in the post and Ive checked over the board and it doesnt look damaged at all.
Does anyone have any ideas or something else I can try? I was going to buy some 3.1 ROMs from Amigakit but they arent in stock so that will have to wait.
Sorry for the long post
Thanks in advance
Taj