You can open a terminal and run the program 'xev'. This will open a plain looking window that will capture all the events the Xserver sends to this window. You can move the mouse into this window and press the delete key. This is what I see in my system:
xxx@xxx:~$ xev
[... many lines from mouse movement ...]
KeyPress event, serial 35, synthetic NO, window 0x1800001,
root 0xa7, subw 0x0, time 649387, (-4,16), root:(439,52),
state 0x0, keycode 119 (keysym 0xffff, Delete), same_screen YES,
XLookupString gives 1 bytes: (7f) ""
XmbLookupString gives 1 bytes: (7f) ""
XFilterEvent returns: False
KeyRelease event, serial 35, synthetic NO, window 0x1800001,
root 0xa7, subw 0x0, time 649497, (-4,16), root:(439,52),
state 0x0, keycode 119 (keysym 0xffff, Delete), same_screen YES,
XLookupString gives 1 bytes: (7f) ""
XFilterEvent returns: False
xmodmap(1)output look like? How aboutxmodmap -pke | grep Delete? – sarnold Jul 4 '11 at 8:42