"dead keys" (accents) not working

Hello,

I have a very strange issue with my Belgian azerty laptop keyboard.
All dead keys, those are the keys used to place accents (¨ , ^ , ´ ,
` , ~) above letters, are not working when I try to create a letter
with an accent. However, when I keep the dead key pushed, after a
second or so, an entire set of the dead key appears (e.g. ^^^^^^^^)
after which I can type my character which will now have an accent
above it (e.g. ^^^^^^^^ê). Of course, this is not a suitable solution.

I know the keys are working (if I try to use the other non dead
characters on the same key, they work immediately) and nothing is
wrong with my keyboard. So I'm figuring it must be some setting
somewhere.

Any ideas?

Yves