I open Vegas, import a clip, click the little green cross that opens FX and all the Boris and Sony filters appear. At least half the Boris filters crash Vegas if I try and apply them to the clip.
All my clips are AVCHD 1080p. But it's a good clue, I'll render to something else and see what happens.
EDIT: I don't think it's a codec thing, I tried MPEG 2 and Lagarith Uncompressed AVi and same problem.