No USB Connection with Arduino Uno Rev3

Hi Arduino Community,

I bought an Arduino Uno rev3 clone from china several months ago.
Link to the Product: http://www.fasttech.com/products/1008/10000015/1001700-arduino-uno-r3-rev3-development-board

I was able to upload the blink sctech with no probems. Everything worked fine.
After a few months I had some spare time to experiment with the arduino.
But I it was not possible to conncect the board with the pc.
Neither Windows 8.1 (64bit) nor Ubuntu 14.04 (64bit) were capable to regcognize the board.
The ON-LED shines green and a orange led blinks while board is plugged in with USB and PC.

I allready tried it with diffrent USB cables and on two other PCs (Win 8.1 64bit / Win 7 64bit) with no success.

Please help me. Thanks in Advance!

What do you get with dmesg on Ubuntu when you plug an unplug it?

I got this output with dmesg | tail while the arduino is pluged in and after unglugging it

[26606.285998] usb 2-4: device not accepting address 16, error -71
[26606.398024] usb 2-4: new full-speed USB device number 17 using xhci_hcd
[26606.398168] usb 2-4: Device not responding to set address.
[26606.602036] usb 2-4: Device not responding to set address.
[26606.805793] usb 2-4: device not accepting address 17, error -71
[26606.917796] usb 2-4: new full-speed USB device number 18 using xhci_hcd
[26606.918011] usb 2-4: Device not responding to set address.
[26607.121715] usb 2-4: Device not responding to set address.
[26607.325601] usb 2-4: device not accepting address 18, error -71
[26607.325660] hub 2-0:1.0: unable to enumerate USB device on port 4

I don't know how to read this output but I guess something seems to be wrong...

That does look very odd.

Have you tried another USB cable, and/or have you got another board you can try?

tried it with another USB cable. Same result...
Unfortunately I do not have another board to test.

[11938.152832] usb 2-4: device not accepting address 11, error -71
[11938.264819] usb 2-4: new full-speed USB device number 12 using xhci_hcd
[11938.264959] usb 2-4: Device not responding to set address.
[11938.469042] usb 2-4: Device not responding to set address.
[11938.672882] usb 2-4: device not accepting address 12, error -71
[11938.784944] usb 2-4: new full-speed USB device number 13 using xhci_hcd
[11938.785127] usb 2-4: Device not responding to set address.
[11938.989107] usb 2-4: Device not responding to set address.
[11939.192971] usb 2-4: device not accepting address 13, error -71
[11939.193054] hub 2-0:1.0: unable to enumerate USB device on port 4

Probably the USB Driver is broken? What do you think chilliTronox?
PS: Thank you for your help

It looks like there is a problem with the USB code in the USB chip, but I can't see how you would have caused that.