When performing a copy to an external USB, Firewire, or eSATA drive, you receive the following error:

A problem was encountered with the operation of Disk <n>. The device is not functioning or may be configured improperly (31). The error (31) indicates a general device failure, which suggests that there was a problem with the external USB, Firewire, or eSATA interface or the external drive itself. For example, magnetic interference from an improperly shielded or defective USB, Firewire, or eSATA cable could be responsible.
Make sure the USB, Firewire, or eSATA interface cable is positioned to avoid close proximity with any monitors, florescent light fixtures, speakers, power cords, etc. Some OEM USB, Firewire, and eSATA cables are poorly shielded and can cause unpredictable behavior. If the trouble persists, try another cable. 

If you are connecting the hard disk through a USB hub, try bypassing the hub and connecting the device directly to a USB port on the computer. The hub may be introducing interference. Likewise, if you are connecting the external drive via an add-on USB, Firewire, or eSATA controller card, the card may be defective. Try attaching it to a native port on the computer.

While less likely, the problem also can be caused by a faulty filter driver, which may be intercepting and corrupting requests by Casper to access the external drive. Try performing the copy with the system running in Safe Mode to ensure non-essential, third-party drivers are not loaded.

Follow this procedure to start your computer in Windows Safe Mode:

1. Restart your computer. 
2. Press F8 when prompted. If Windows fails to display the Windows Advanced Options menu, restart your computer again. Press F8 after the BIOS completes the POST process, but before Windows displays any graphical output.
3. Select Safe Mode or Safe Mode with Networking from the Windows Advanced Options menu.

• Windows 7
• Windows Vista
• Windows XP
• Windows 2000