About a week ago, on a NetBSD-1-6 machine, my '0' key stopped working.
KP_0 works fine (when numlock's on, of course).

The key works fine on the console, and in one X application (rdesktop),
but in all other X apps it does not work.

When pressed, xev reports:

FocusOut event, serial 25, synthetic NO, window 0x3200001,
    mode NotifyGrab, detail NotifyAncestor

FocusOut event, serial 25, synthetic NO, window 0x3200001,
    mode NotifyUngrab, detail NotifyPointer

FocusIn event, serial 25, synthetic NO, window 0x3200001,
    mode NotifyUngrab, detail NotifyAncestor

KeymapNotify event, serial 25, synthetic NO, window 0x0,
    keys:  53  0   0   0   0   0   0   0   0   0   0   0   0   0   0   0
           0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0

As opposed to the following for '9':

KeyPress event, serial 25, synthetic NO, window 0x3200001,
    root 0x35, subw 0x0, time 1760774313, (29,112), root:(582,218),
    state 0x10, keycode 18 (keysym 0x39, 9), same_screen YES,
    XLookupString gives 1 characters:  "9"

KeyRelease event, serial 25, synthetic NO, window 0x3200001,
    root 0x35, subw 0x0, time 1760774367, (29,112), root:(582,218),
    state 0x10, keycode 18 (keysym 0x39, 9), same_screen YES,
    XLookupString gives 1 characters:  "9"
 

xmodmap doesn't show anything interesting: 

...
     18         0x0039 (9)      0x0028 (parenleft)      
     19         0x0030 (0)      0x0029 (parenright)     
     20         0x002d (minus)  0x005f (underscore)     
...

X does have XKB configured, but I've never done anything special to it.

Any thoughts where else I should look?

-- 
David Maxwell, david@vex.net|david@maxwell.net --> Although some of you out
there might find a microwave oven controlled by a Unix system an attractive
idea, controlling a microwave oven is easily accomplished with the smallest
of microcontrollers. - Russ Hersch - (Microcontroller primer and FAQ)