Having Some Shut Down Problems

Hello,

I was wondering if anyone has ever had difficulty shutting down or restarting their mac. I have a MacBook Pro and sometimes whenever I shut down or restart my mac everything seems to be going fine--desktop etc. vanishes>goes to the blue screen with the loading circle (the one that looks like a analog clock with extra numbers)--but then it just keeps on loading. I eventually get frustrated and just hold down the power button until it turns off.
Does anyone know what the problem could be, and how to fix it?

Thanks,

MC

Did you try resetting the SMC (System Management Controller) ?