driver issue with Arduino Uno on Windows 7 64 bits

First of all , happy new year to all of you.

I have an arduino uno that I've bought with the starter kit. So far it was working fine, I've managed to upload a program several times. This afternoon, i had an issue uploading a program. I've noticed that it was not visible in the device manager.

I've tried to unplug/replug the board, but os doesnt see the connection (no "device" sound). I've tried another cable, and another usb port. I've uninstalled and reinstalled Arduino Ide and drivers. I've reset windows 7 com ports I've tried a manual install of the arduino uno but i got the error 10 unable to start device. I've tried other pc with Windows 7 and linux, but it is not detected as well.

I've performed the loop-back test, but i get stuck before being able to check communication, as board is not detected.

From the outside it seems to work. When it is plugged, led blinks 3 times and then stays lit.

I'm quite stuck :-/ What are the remaining options to me?

Thanks for any feedback you might give.

After countless trials, uninstalls and reinstalls, I was about to give up. I've tried it on another computer where it was detected, so i uploaded blink.

Now it is now working again on my computer, and i have absolutely now idea why, with the same port and usb cable.

Somehow i'm quite puzzled