Logic Express Doesn't Like My G3 Ibook, Logic Express claiming it requires G4! Options

[Dunepilot]

I have just picked up Logic Express 6 so that I can finally stop having to use OS 9 for anything (to ditch Logic Silver 4.8).

However, I'm getting a wierd error on my 800MHz G3 iBook when I launch the application, that says

"CUBE needs Altivec compatible cpu (G4 and up)" and then I have to quit the app.

Logic Express should work with a G3, so what is this 'CUBE' thing referring to? I have an edirol UA-30 USB audio solution (using core audio driver) and an emagic MT4 USB MIDI box that I want to use with Logic. I have a feeling the problem is being caused by the UA-30 in some way, because logic launches okay if I don't have this plugged in (though I get another error telling me I have no audio interface plugged in).

Can anybody shed any light on this?

Thanks in advance
Dune