Have WDC WD10 EACS-00ZJB0 and 32ZJB0 connected to USB. Copied file about 40 GB to both. The speed for 00ZJB0 was about 5 times more than for the 32ZJB0 (on Windows Vista Ultimate 64 bit, 5 MB/s and 1 MB/s). But biggest issue with 32ZJB0 was a lot of errors in copied file (used fc sourceFile targetFile /B and no errors for 00ZJB0). Then swapped the disks between USB adapters and the issue reproduced the same way: 32ZJB0 was 5 times slower and had a lot of errors comparing with the source file.
What could be the issue and how it could be attended to?