tsuki, this sounds like it might the bug which I recently fixed with the Grass Clump object. Changing some parameters in the object resets its transformation (i.e. its translation, rotation and scale), ignoring the values you put it. I am not sure, but it could also give the wrong results after loading a file. The way to get around this bug is to make a change to any of the translate, rotate, or scale values and then all should be correct.
This bug has been fixed for the Beta.
Matt