This may be a silly question but you don't have a wireless keyboard do you Mahud? It's just that I do, and it sends a signal to the PC via a USB receiver which plugs into the front of my computer. My PC is sat underneath my desk. Because of this, if my keyboard is moved to certain parts of my desk then typing starts to go wrong- a few seconds delay between typing and the letters appearing on screen, and many letters not appearing at all and so the result is words with half the letters missing. I think what is significant is the amount of desk that the signal has to pass through. This probably isn't relevant to your problem but it would be nice if your issue could be resolved by simply keeping your keyboard closer to the PC.