Bad pump can be:

- Corrupted builder file.
- Serial port trouble, serial cable trouble.
- Disk drive trouble.
- Connection between mobo and disk drive trouble.

Although you say you checked some of those things, what steps did you do to truly rule them out with certainty? For instance, what grounds do you cite for expecting the 20gb or 160gb drives as being truly good? Have you made sure the serial cable is good by looking at the device in a terminal program? Have you made sure the IDE chip isn't bad by looking at a boot log? Does Mark supply a checksum for the builder files (not sure?)?