according to gbatek, the 04000000h range is for I/O ports.
according to sourceforge, there has been a new default arm7 binary released 2 hours ago. so try updating and see if that fixes it.
if that doesn't work, you could try building the default arm7 binary from svn and see if that works. that should tell us if it already has been fixed in svn or not.
btw, are you using maxmod for sound or something else.
and WinterMute, my nickname is vuurrobin. double 'u', double 'r' and preferebly all lowercase.
edit: you also might want to update the docs at http://libnds.devkitpro.org/