What's wrong with communism?

Know that when i say “communism” that I am strictly speaking of an economic system where the government controls all enterprise, decides upon and distributes pay to its citizens. Assume that all government officials are democratically elected as U.S. officials are. I have argued with dozens of friends, teachers, and family members on whether or not communism is useful or even possible. Most of the time it boils down to two problems of human nature: selfishness (Why work if youll get paid anyways?) and political corruption. I have found many to be somewhat hobbesian natures (having opinions similar to those of Thomas Hobbes, that human beings are inherently greedy, evil, and plain old bad in nature. He believed that humans were unfit to rule themselves and thought that tyranny was the only way to do what is right for the people.) What are your thoughts on and criticisms of communism? Ways to make it work? Is a Marxist path to communism, or Marxism, necessary?