Please, which model MacBook Pro? Any more details on the enclosures etc.?
No rush. But it's often useful to consider the hardware when puzzling over issues with devices on USB.
viewtopic.php?p=3147#p3147 for a recent example.
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Here: MacBookPro5,2 with 8 GB memory and a variety of USB drives, at least one of those drives nearly always used with an old-ish hub that has an independent power supply –
Sitecom USB 2.0 Dock CN-022:
Product ID: 0x0022
Vendor ID: 0x182d
Version: 1.00
Serial Number: 1111111
Speed: Up to 480 Mb/sec
Manufacturer: Sitecom CORP.
Location ID: 0x26400000 / 3
Current Available (mA): 500
Current Required (mA): 0