Assuming that you are on top of the jumpering for master and slave drives (beware the drives that have a 'single' jumper when they are alone), and that you are using good-quality 80-wire cables, there is little further that you can do but invest in an ATA-133 PCI card. Not only may you then have future 48-bit LBA capacity for drives of more than 128GB, but also, in case the present controller is playing up, an ATA controller that is independent of the MLB's controller.

Good luck.

de
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(60x) 13DT + 3PB + PTPro; (G3) 7DT/MT; (G4) 3T + PB. System 8.1 to OS 10.5.8