I'm sorry that you are having some difficulties with your Craftsman Mower. I did a little research for you at Managemylife.com and found an expert answer to a similar question that may help until your expert can respond to your specific question. The link is attached below. If you decide to schedule service and have a qualified technician help you, I have also attached a link to Searshomeservices.com. I hope these links will help until your expert can respond.
It sounds like the belt may not be on all the pulleys correctly. If the belts are routed properly but on the outside of a belt keeper there will usually be smoke and a lot of vibration. Give that a look and if it looks normal you may want to contact the store where purchased to see if they can get someone to come take a look at it.