My laptop is running Windows 7 Ultimate Service Pack 1. I'm using internet through Huawei 3G USB Modem E1550, due to signal issues, I do not connect the modem directly to my laptop, instead, I connect it via USB 2.0 extension cable, now the problem is that, when I attach USB flash drive to the remaining of the USB ports, I get notification bubble that says:

USB Device Not Recognized

One of the USB devices attached to this computer has malfunctioned, and Windows does not recognize it. For assistance in solving this problem, click this message.

And this thing occurs with any port that I try, as long as the extension cable is connected and USB Modem is connected with that. While everything works fine if cable is removed. I tried the same by connecting the modem directly with my laptop ports without cable intermediated, and problem doesn't occur, So there's something to do with the cable. Though my extension cable is not very expensive, but the package says that it supports USB 2.0, and I also tested the data transfer rates of the cable, and it works fine.

I also looked up what device manager displays while flash drive is connected but not working, and all I see under "USB Serial Bus Controllers" category is "Unknown Device" with yellow exclamation mark which clearly suggests some issue with the device.

I cannot use Modem without extension cable since indoor network of my provider is very low.

What can I do to get my Flash drives working under such situation..........??


USB cables weren't designed to be run over long distances (over ~16 feet). The signal degrades over that span and it needs to be boosted.

You want something like: USB 2.0 Booster Extension Cable

Also, like @Hyppy said, you can also use a powered USB hub(separate power cord than the USB that comes from the computer) to provide more power in case the booster cable does not pass the power through to the terminal node on the USB chain.

  • Under the USB 2.0 spec, (non-active) extension cables are "prohibited". See page 92 of the main USB 2.0 specification in the zip file here : usb.org/developers/docs . It is likely that the combination of the the extension cable and the 3g card is messing up the attenuation or other electrical property of the cable. Using the abovementioned USB Booster extension instead, is basically the same as plugging in a 1 port hub with a long lead, which is okay and should, as he says, work much better. – camster342 May 28 '11 at 13:17
  • I've noticed problems with two short USB extension leads (one was just 10cm) on two different Windows laptops. Then seem to work OK for the first month, and then go weird. Yet all printers and scanners come with their own 1 metre lead, and can cope with that distance. – MerlinMags Sep 7 '16 at 15:00

If the cable is long, try putting a powered USB hub in the middle. It sounds like the long cable and the power requirements of the modem combined are taking too much power for your other devices to work.

  • The cable length is about 1.8 meters, and yes, my modem has LED representing the connection. But I wonder why this trouble occurs only with Windows, I'm dual booting with Ubuntu 10.10, and this problem do not exist in Ubuntu, though I get slow data transfer rates if I transfer files to flash drive while the modem is connected via cable, but at least I can access flash drives. – Kushal Mar 18 '11 at 17:57
  • @Kush You really should include that Windows vs Linux discrepancy in the question, it's a significant data point and changes the picture a lot. – Matthew Najmon Dec 17 '14 at 14:55

You should check the device manager to ensure that all the driver software for your USB port was installed properly.

To do this,

  1. Right-click "My Computer"
  2. Click "Manage"
  3. Click "Device Manager"
  4. Expand "Universal Series Bus Controllers"

Anything that appears in yellow with an exclamatory symbol needs to be installed or reinstalled.

Download the drivers for those and re install.

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