Thank you for directing me towards a cable problem. All I did was to remove the USB-cable from the computer, and without a restart plug it back in again. Since then, all day to day, it has been blinking, no matter restart or reinstallation of drivers. Changed cable and all is fine.
That is; allmost. The reason for my unplugging of the USB-cable was an irritating problem of silent gaps in every tunes I play. A cuple of times in every tune.
Now I have to find someone who can help me With that.
Again, Thanx!!