Dock pop-up menus not working?

I have an iBook G4 12" Power PC running Tiger 10.4.11.

I just noticed my pop-up menus in the dock don't work when I ctrl-click. I have no idea how long it's been like this, as it's not something I use often. Quite some time ago I customized all of my dock icons, including the Finder icon. Could this have something to do with it? Is there a way to fix it without having to reinstall Tiger or something drastic like that?

so ctrl-click works everywhere else yes?
im not sure if this is just a leopard feature, but on my dock, if i click on an application, and keep it clicked (hold down the mouse button), after 2 seconds or so the right-click menu appears. have you tried this?

Yeah, I've tried that. Nothing.

The pop up menus do work everywhere else, just not in the dock. It's so weird.