Backup Error

Getting the following error when I try to backup to one of the external USB hard drives. Any help would be appreciated.

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Log Entry Details
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Type: Error
Date and time: 7/17/2013 10:24:33 AM
Backup plan: Daily USB Backup
Task: Full backup
Code: 66,038(0x101F6)
Module: 1
Owner:
Message:
Operation with partition 'D:' was terminated.
Details:
Write error.

Error code: 0x70004
$module = "disk_bundle_vs"
Tag: 0x9D2DE1F088CBC4D8
The operation is not supported.

Error code: 0x4000E
function = "WriteFileNoCache",
$module = "disk_bundle_vs"
Tag: 0x7CEB2CDC9FB121D3
Incorrect function

Error code: 0xFFF0
code = 2,147,942,401 (0x80070001),
$module = "disk_bundle_vs"
Tag: 0xBD28FDBD64EDB8E0
Additional info:
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Error code: 502
Module: 1
LineInfo: a164035b3ff39287
Fields: $module : disk_bundle_vs
Message: Operation with partition 'D:' was terminated.
Details:
Write error.

Error code: 0x70004
$module = "disk_bundle_vs"
Tag: 0x9D2DE1F088CBC4D8
The operation is not supported.

Error code: 0x4000E
function = "WriteFileNoCache",
$module = "disk_bundle_vs"
Tag: 0x7CEB2CDC9FB121D3
Incorrect function

Error code: 0xFFF0
code = 2,147,942,401 (0x80070001),
$module = "disk_bundle_vs"
Tag: 0xBD28FDBD64EDB8E0
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Error code: 4
Module: 7
LineInfo: 9d2de1f088cbc4d8
Fields: $module : disk_bundle_vs
Message: Write error.
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Error code: 14
Module: 4
LineInfo: 7ceb2cdc9fb121d3
Fields: function : WriteFileNoCache, $module : disk_bundle_vs
Message: The operation is not supported.
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Error code: 65520
Module: 0
LineInfo: bd28fdbd64edb8e0
Fields: code : 2147942401, $module : disk_bundle_vs
Message: Incorrect function
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Acronis Knowledge Base: http://kb.acronis.com/errorcode/

Event code: 0x000101F6+0x00070004+0x0004000E+0x0000FFF0+0x80070001

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