An external hard disk that is based on the IEEE 1394 standard is not detected on a Windows Vista-based computer

You connect an external hard disk that is based on the Institute of Electrical and Electronics Engineers, Inc. (IEEE) 1394 standard to a Windows Vista-based computer. However, the external hard disk is not detected.

This symptom occurs on dual-capability external hard disks that can be connected by using an IEEE 1394 connection or a USB connection. However, this symptom only occurs when the external hard disk is connected by using an IEEE 1394 connection.

This problem occurs if the external hard disk does not support the MODE_SELECT parameter.

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To resolve this problem, set the LegacyFlags registry value to a hexadecimal value of 200. To do this, follow these steps:

1. Click Start
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   , type regedit in the Start Search box, and then click regedit in the Programs list.
   
   
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   If you are prompted for an administrator password or for confirmation, type your password, or click Continue.
2. Locate and then click the following registry subkey, where device_ID is the identification number for the external hard disk, and hardware_key is the key for the external hard disk:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\SBP2\device_ID\hardware_key\Device Parameters
3. On the Edit menu, point to New, and then click DWORD Value.
4. Type LegacyFlags, and then press ENTER.
5. Right-click LegacyFlags, and then click Modify.
6. In the Value data box, type 200, click Hexadecimal in the Base area, and then click OK.
7. Exit Registry Editor.

For more information about how to resolve this problem, contact the manufacturer of the chipset in your computer. For information about how to contact the manufacturer of the chipset in your computer, visit the following Microsoft Web site:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.