USB devices not recognized or STOP ERROR 0x9F

This article provides the information on "USB devices connected to USB 2.0 or 3.0 ports will cease to be recognized, or a 9F stop error".

USB devices not recognized or STOP ERROR 0x9F.

USB devices connected to USB 2.0 or 3.0 ports will cease to be recognized, or a Windows 9F blue screen (STOP) error occurs after the following actions:

• The system wakes from sleep or hibernate.
• A USB device is disconnected unexpectedly then reconnected.
• A USB device is disconnected correctly then reconnected.
• The system is rebooted.

The issue may also occur intermittently during active system use. Disconnecting/reconnecting the USB devices does not resolve the issue.

When the error is present, attempts to shut down the system through Windows will result in a freeze on the "Shutting Down" screen, requiring a hard shut down by pressing and holding the power button until the system power off.

This issue has been documented to occur on the OptiPlex 3020, the Latitude 3340, and the Precision M3800 with the Windows 7 professional x64 operating system. It is assumed this issue could occur on systems with similar operating systems chipsets.

Install Microsoft Hotfix KB2895729

The Microsoft hotfix in KB2895729 resolves this issue. It can be found on the Microsoft support site.