Comment 26 for bug 250695

I can confirm that this happens in Karmic (GNOME 2.28.1, Rhythmbox 0.12.5). The keys involved don't need to be any special media keys, they can be any shortcut specified with the GNOME Keyboard Shortcuts tool. And it only happens when Rhythmbox is the focused window.

My steps to reproduce:

1. Open Preferences > Keyboard Shortcuts
2. Set "volume down" to something like Ctrl+Alt+Down
3. Open Rhythmbox
4. Start a track playing
5. With Rhythmbox as the currently focused window, press Ctrl+Alt+Down or whatever you bound the volume control to
6. Observe: the volume does not change, Rhythmbox freezes (no visual updates or interactivity) for some period of time, and finally the UI becomes responsive again
7. Switch to another window or workspace
8. Use the same key binding to adjust the volume
9. Observe: the volume adjusts immediately, and Rhythmbox does not freeze