Cat keeps attacking other animals! HELP!?

I have two cats Maci and Zack. Recently they had a litter of kittens which are now 5 weeks old as of today (3/11/2011). Even though the kittens are starting to not need Maci as much she will not allow Zack nor our two dogs ANYWHERE near her at all without attacking them violently. It has been a long 5 weeks and have no solutions or hope for the future. Is this normal and will it ever go back to normal??? Why is she doing this and will she stop??