Troubleshooting "USB device not recognized" error on Windows

Last Updated: Jul 08, 2014 03:13PM EDT
Some users who have a Windows XP or Windows 7 operating system have reported a "USB device not recognized" error when attempting to connect their Q sensor via the USB cable. The sensor's contents may still be accessible when connected to a Mac, rather than Windows, computer.

Here are the recommended steps for troubleshooting this issue on a Windows machine:
1) Attach the Q sensor to your computer via USB cable, then press the sensor button.  Wait for the purple light to appear on the sensor.
2) Click on the Windows Start button, then type "devmgmt.msc" in the search field.  Hit Enter to open Device Manager.
3) At the bottom of the device manager list, expand the "Universal Serial Bus Controllers" tree.
4) A list of USB controllers will appear. If there is a problem with the USB driver, you should see an "Unknown Device" with a yellow exclamation mark icon.
5) Right click on "Unknown Device" and choose Uninstall > OK. This will remove the malfunctioning device driver.
6) Right click on any of the other devices in the list and choose "Scan for hardware changes". This will install a new USB device driver.
7) Check Windows Explorer to see if the Q sensor appears as a removable drive.  (The drive letter will vary by computer.)
8) If the drive is still not accessible, the following workarounds may resolve the issue:

Workaround 1: With the sensor in its mounted state (purple light on sensor) but not showing up in Windows, reboot the machine. After the reboot, go to Windows Explorer. The sensor's drive and its contents may be visible.  If so, select all dated folders containing .eda files and archive them (i.e. cut and paste from the sensor to your computer's hard drive.)
Workaround 2: While connected to the computer via USB cable, repeatedly press the sensor button to mount (purple light), then unmount (red light). Do this about 10 times, pausing 10 seconds between each attempt. This will sometimes make the removable drive appear in Windows Explorer.  If so, select all dated folders containing .eda files and archive them, removing them from the sensor.
Workaround 3: If you have access to a Mac computer, try connecting the sensor via USB and mounting it by pressing the button.  When a sensor has many folders on it, it can often be mounted on a Mac when it can't be mounted on a Windows machine.  If so, select all dated folders containing .eda files and archive them, removing them from the sensor.

If any of the workarounds above resolve the issue, you can avoid it in the future by ensuring that firmware version 1.81 is installed if it's a V2/Bluetooth sensor, or 1.51 if it's a V1/pod sensor.  The firmware version appears at the top of an .eda file when opening it with a text editor.  The firmware can be accessed from the Downloads section of

It's also a good idea to periodically remove data folders from the sensor, moving them to an archive location.

External resources:

Searching Microsoft forums reveals a number of similar cases involving Windows failing to recognize generic external drives. The solution that appears to have the most positive votes so far came from a microsoft forum and it is similar to our recommendations. Some of the top solutions are shown on this thread :

Also, refer to this MS article:

See also this thread:
(see in particular the two procedures in the the posting from Matthew2809)
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