[xmonad] First keystroke is lost

[Peter]

Hi
After restarting X , I have a problem that I already had some time ago, 
but I can not remember if/how I resolved it ( as far as I remember, a 
similar issue has been discussed in the forum , but I can not remember 
that neither)
The problem is, after switching to another window ( console ) , the 
first keystroke is always lost , although the cursor shows that the 
window has already the focus.

Can anybody help

Thanks a lot
Peter