Help troubleshooting keyboard shortcut

Hi,

I use gnome on a stable system.  I set my "preferred browser" to
chromium.  I set a "keyboard shortcut" to launch my browser: Mod4+W.

90% of the time when I press Mod4+W, the browser appears.

10% of the time when I press Mod4+W, the browser does not appear.
When it doesn't work, I try again and the browser will appear,
although when it is in the "bad" state I generally have to issue
Mod4+W 3-4 times before I get the desired response.

Can someone recommend an approach to identify the culprit?  For example
- check ctrl-alt-f1 for errors
- install KDE
- try a new keyboard
- etc...

Thank you,

Chris