TMPG is not best choice for encoding SVCD (low quality)
NeroVisionExpress made bugs in SVCD structure.
Best results when encode in Vegas (if need 5.1MPEG sound encode it separately from 5.1 AC3, prepared in Vegas, to 5.1 mpa with HyperCubeTranscoder, then multiplex in TMPG), make project & burn in Ulead DVD Movie Factory (it fully support 5.1 sound and 2 audio streams in SVCD).