The orignal HDD has something installed on it which makes the computer crash. Perhaps it is from another Amiga with a more moderm processor. Or it does not have the file system stored on it needed to read the boot partition. Or it's just corrupted.
You should connect it to a PC and install an MBR on it (just to delete the Amiga partition table). But don't create partitions and don't format anything, or all your data will be lost.
Then connect it to the Amiga and run a RDB recovery program (e.g. RDB-Salv or RDBRecov) in order to recreate the partition table from the existing partitions.
Alternatively you could try to connect it to the second channel of the EIDE'99, boot from floppy or from another HDD and then run IDEfix to mount the original HDD. If you are lucky, it won't crash this time and you can use your favourite partitioning program (e.g. HDToolbox) to repair its RDB.
Bye,
Thomas
