since a week or two ago I have this really strange Ctrl key issue... it *sometimes* stops working as a qualifier key (in combination with the up/down cursor keys). I noticed it in two different programs. First I thought my keyboard was failing, but it's the same thing with a different keyboard.
The really weird thing is that I can't reproduce it at will. Right now it's not working for example, but it might work again in 5 minutes. Or in two hours. I didn't spot a pattern. (Sometimes I seem to be able to get it to work again by restarting the program I want to use it in, but not always.)