Why is the government trying to guarantee anything right now, like warrantees for instance?

In the case of GM it is designed to stabilize consumer confidence. Unfortunately we really should have no confidence in a failing entity. In the case of Fannie/Freddie it was to instill investor confidence so that they would make the loans. Both are just a means to get people to spend money. There is this idea now that the economy must always continue growing. The only way to accomplish this is to keep people spending with reckless abandon. Frankly I wouldn't buy a GM or Chryler car at this point if they were selling them for a dollar. I don't care who guarantees their warranties.