Keyboard shortcut works with Eterm, but not with Terminal

[Tom K]

I'm replacing Eterm with Terminal under xfce4 4.4, and everything's good 
so far, except for one keyboard shorcut in one application. When I run 
irssi in Eterm, I can change the irssi window with 
Alt+Right/Left/Up/Down - when I run it in Terminal, those keys no longer 
work. I can still change the irssi window with Esc+Right/Left/Up/Down, 
but I'd prefer Alt.

I've looked through both my xfwm4 and Terminal settings but I can't see 
anything that would cause this - specifically, there is no other 
shortcut mapped to those key combinations. I'd be grateful for any 
suggestions.

Thanks
Tom K