On the A4000T with OS 40.70 in ROM, it lacks the workbench.library. Therefore you have to use the special WB 3.1 disks which have workbench.library on them.
Either that or it's getting upset because the 68060.library is not present when booting WB from disk.
If it helps I can send you a OS 3.9 emergency disk image (which you will have to edit depending on your CDrom config) which you can use to boot to install OS 3.9 from CD.
If you install Boing Bag 1, make sure you install Boing Bag 2 immediately afterwards, because BB1 causes problems with the SCSI controllers on A4000Ts.
