Thanks for the quick responses. I was trying to cut the stars on medium weight card stock. I will download the stars and will give them a try.
The weight is not really the be all and end all when it comes to cutting, different cards have different densities and stiffness and it is the density and stiffness that often determines how well it cuts.
If you have a selection of different cards it might be worth trying a few different ones with standard sharp stars, if you find that they cut fine from some other card then you can safely deduce that this card is not great for cutting and reserve it for simpler, smoother curved projects. You will also have a card which you know cuts fine so if you have problems with cuts you can try on a media you know cuts well to help determine if it is the media that is the problem or something else.
Let us know how you get on with the rounded stars