Macbook Pro will NOT shut down
I bought a new 13" Macbook Pro about 3 months ago (my first mac). For some reason, last night was the first time that I tried shutting it down. However, when I go to shut it down, it seems to work, the screen goes black, then it boots up again as if I restarted it instead of shutting down. It also won't go into sleep mode in the same way. If I put into sleep in any other way than closing the screen, it will go black, then come back on.
I'm not sure what to do. I've tried unplugging the power and external devices before shutting down. I've logged out of my user and shut from their, with no success. I've seen from my internet research that this is a problem that other people have had, but there don't seem to be any clear solutions. Has anyone been able to figure this out? Or am I in over my head and should contact Applecare?
Thanks.
Macbook Pro 13 inch, Mac OS X (10.6.5)