Hmm, sounds like a Keymap problem to me.
Do you have the "Workbench: Tools 3.0" disk also?
There is a tool called Input in the Prefs dir.
Start it and select a different Keymap that fits to your locale. Maybe the keymap is not a standart Workbench one, like some cracker groups, game developers, intro/demo coders create for themselves to give access to many keypresses at once just by a single keypress. In this case you can delete it.
If you want to see what keymap is in use, then start this Input tool and look at which keymap is selected.
Then insert your Workbench System disk and delete the keymap from your Devs/Keymaps dir.
I hope that helps. :-)