My PC (Windows 8.1) does not find the Arduino Uno

My PC, a new HP 250 G3, running windows 8.1 does not find the Arduino Uno. I have gone through all the troubleshooting guide steps and also disabled the driver signature enforcement in Windows But NO. My board, Arduino Uno R3, was bought from Elfa Distrelec AB (www.elfa.se) and I believe the serial number is U00885376. The board seems okay, power LED is on and the yellow LED is blinking. There are no jumpers on the board. USB cable is okay.

The problem is a communication problem and these are the messages from the Arduino 1.0.6 environment:

" Done uploading Binary sketch size 1,082 bytes (of a 32,256 byte maximum) avrdude: st500_getsync(): not in sync: resp = 0x00 "

and

" avrdude: usbdev_open(): did not find any USB device "usb" "

Any solution to this ?

se om driver finnes i enhetsbehandlingen (is driver present? - system - properties)

..enhetsbehandlingen ? Swedish is okay but I have all settings in English. I believe this is the device manager.

Device Manager . . Ports(COM & LPT) Communications Port(COM1) Communications Port (COM1) properties Driver Communications Port(COM1) Driver provider Microsoft . . Digital Signer Microsoft Windows

Update Driver

But when I update the driver " Browse the computer for driver software " and choose

C:\Users\ .... \arduino-1.0.6\drivers

restart the Arduino 1.0.6 and then upload the sketch, there is no change !?

It does not seem like disabling the driver signature enforcement had any effect. What do I do wrong ?

Okay I don't know what I did differently this time but now I have the arduino driver in properties BUT...

" Arduino Uno (COM1) Properties

Device status This device cannot start (Code 10)

The specific request is not a valid operation for the target device "

Driver Provider Arduino LLC Driver Date 1/4/2013 Driver version 1.0.0.0

What does this mean ?

I started with the "Arduino 1.0.6 Windows Zip file for non admin install", experienced the problems described, and I'm now stuck with the following:

In Windows Systems/Device Manager Arduino Uno (COM1) Properties Device status " This device cannot start (Code 10) The specified request is not a valid operation for the target device "

AND the Serial Port option under Tools in Arduino 1.0.6 is empty !?

I dont know how to proceed from here any suggestions ?