Formatting drives in 2.5 inch external enclosures

I have a somewhat generic BlueEye O2 USB2.0/FW400 2.5" external drive enclosure. I was recently trying to format some older laptop drives (2.5" PATA) and discovered that the "erase" and "partition" options in Disk Utility (Mac OS X 10.5.5 version) always fail when I was connecting using USB but work fine when connecting using FireWire. The error message is along the lines of I/O error or something. I'm sure glad my MacBook has FireWire...

I wonder whether this is a limitation of the BlueEye chipset or the Disk Utility software. I really should upgrade 10.5.5 to 10.5.8 too...