iTunes Problems (freezing)

I bought my iMac last week and everything had been going fine with iTunes until yesterday when it started to freeze (not open) when I activated it. I had to "force quit" to get out of it. I shut down the computer several times, still nothing. Just as I was typing this though, it worked so it appears to be a sporadic problem. Is this a problem for everyone, or have I just got a dud?