0. Check if you can type the key in a wxWidgets demo/sample application
1. You can try to disable the keybinder plugin
2. Close C::B, remove your C::B configuration folder and hope it is fixed, start C::B
p.s. 2. should be... Close C::B, rename the C::B configuration, start C::B. If the problem is fixed remove the fixed one and restore the buggy one. If it is broken again, post your config here, so someone can see what is wrong.