The Presentation Zen blog had a post today about play and refers to the beginner's mind. I touched on the beginner's mind before in my Diversity of Thought post. The PZ blog does much better job of stimulating thoughts about play than I could so I thought I'd just direct you there. Read the post with a problem you have in mind.
Problem solving often requires a fresh perspective. Play frees the mind from whatever rut you are in.