Your note that the drives worked fine on a Windows machine but not on the Mac makes me think of other possibilities:

- Mac had problem with its USB port hardware, or the software drivers which drive the ports.

- The "Fat32 is slow" issue that I googled about might be mac-specific.

- The USB chipset hardware/firmware on the cheap drives was only tested against Windows machines and never got tested against Macs, or tested against macs with older operating systems, so you're running into an incompatibility between the drives and the Mac, or that specific Mac.
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Tony Fabris