Just my thoughts (just as invalid as anyone else's)
The resultat was because the DEL key return ascii code "46" instead of "127"
46 is the ascii code for dot, so the event occur when i press del and dot grin
On any keyboard I have seen that key will be used for dot and del, dependant upon the state of the NumLock state. There is normally also another del key called Delete (in the insert, home, pg up etc. cluster above the arrow keys on my keyboard). I think laptops also have a separate del key, position changes from manufacturer to manufacturer.
In other words with numlock off both del keys would give the same ASCII code, but differ with numlock on. Note Keycode (where key is on the keyboard matrix) and ASCII key code are not the same thing
Could this be the source of the confusion