sound_seg was -1, which crashes in BOA_INDEX(sound_seg) on 64bit
platforms (by pure luck it doesn't seem to crash on 32bit platforms)
It makes sense to catch this problem much earlier in Play3dSound(),
to avoid executing all the superfluous
Most of the warnings were caused by uninitialized values. Some were in plug-ins that didn't have a break in a switch, causing the memory to be deleted twice.
