'Quit' key hooking in MAME problem (using MultiFE)

[DolansCadillac]

Hey guys - I'm trying to set up a bartop using MultiFE, but I've run into a snag that has probably come up with other frontends. I need to map MultiFE's quit key and MAME's UI Cancel to the same button, but MAME won't acknowledge when the key is hit if it's run through the frontend (run by itself it reads the key without issue). I'm using a custom compile of MAME 0.132 with the no-nag patch and with the FORCE_DIRECTINPUT flag on, thinking that would fix it (nope). This is on a machine running XP 32, SP1 (stock, no updates).

Now on my regular PC (Vista 32, fully updated) the same setup works, pressing the mapped key will quit MAME when run through the frontend. The versions of MAME and MultiFE are identical on both machines. So I'm at a loss as to what could be going wrong here. Anybody run into something similar?

(Hey Space Fractal if you see this, great frontend by the way. Once I get this resolved it'll do everything I need it to.)

[DolansCadillac]

One other thing that might be relevant - I'm also running a volume tray applet that uses hotkeys for volume adjustment, which works fine in MAME. I thought that was odd.