Can't open device | TX LED flashing fast


I am trying to upload a sketch to my UNO board.
I get the message from the IDE "avrdude: ser_open(): can't open device "\.\COM4": Access refused".
By the way when I plug the arduino in, the TX led is flashing very fast.

The COM port and the board typ is the correct one.

I tried unplugging, changing cable, unstalling the board in device-manager and another computer.

Is there any other idea how I might get it to work again?



Somehow more angry replugging helped...