Notice that the keyboard shortcuts have changed considerably since Opera 9.2. The old shortcuts are still available if you choose “Opera 9.2 Compatible” in Tools > Preferences > Advanced > Shortcuts.
I started to notice this when two of my favortite shortcuts:
1. Z to browse previous page in history and
2. X to browse next page in history
were not working anymore.
To get these to work again, all I need to do was to goto Tools > Preferences > Advanced > Shortcuts and check the tickbox “Enable single-key shortcuts“.