Wierd. Never had a prob. But I don't use Carrara for actual modeling, so that might just be me. In Ray Dream at least, if you tried a boolean in the main screen you took your chances, but in the vertex modeler booleans were fairly clean. Since this may or may not be the case in Carrara, I recommend you expand your suite- I believe TrueSpace 1 had a decent boolean engine, and it's free.