In the subject http://boards.dingoonity.org/gcw-development/sdl_mixer1-2-bug/msg112539, Senor Quack seems to have the same issue and had converted the OGG file to WAV to avoid this bug. But I don?t really like this solution. 
I only mentioned that because it occured once on a single OGG file a long time ago on a completely different platform (GP2X). When I later ported the same game to GCW Zero, the problem with that same file did not occur and I've never had a single issue playing OGG files on the GCW Zero.
First off, is it just one OGG file that is causing your problem or do all OGG files cause the same problem?EDIT:
After testing out your source code, first modifying it to use SDL1.2 headers in both ZeroG.cpp and mix_test.h, I verified your OGG would not play, but others would. Pcercuei in IRC chat suggested I check your OGG to see what it contained and it is a OGG video, not an OGG vorbis audio file, as you can see running linux 'file' command on it:
test.ogg: Ogg data, Theora video
You can losslessly extract a Ogg vorbis audio substream from a OGG Theora video file by installing the ffmpeg package and running the following command:
ffmpeg -i input-file.ogg -acodec copy -vn output-file.ogg
I tested this method using your file and successfully played the resulting OGG using your code on the GCW Zero.