The Kickstart (40.70) for the A4000T does not contain the workbench.library. It was removed from the ROM to the Workbench disk's Libs drawer - however the Amiga A1200's Kickstart (40.68) has this already in ROM as soon as the Amiga is powered on. These two libraries could be causing the conflict.
Also the A4000T system disks will load Commodore's buggy 68040.libary which will conflict with Amiga's without a 68040 CPU.
Original AmigaOS 3.1 Disks for A1200
