Not sure on how to tell what week it is. Twice now, my sister's MacBook (1.83GHz, 1GB) has been very slow if it's opened right after being closed. (eg forgot to do somthing before sleeping it) It has a black screen for a minute or more even, but if you're patient, it loads up as it should.
No problems whatsoever with my Core2 MacBook Pro yet...
You could always try shutting it down, taking the battery out and unplugging it, and then holding down the power button for 10 seconds. After that, put it back in, and turn it on holding Command, Option, P and R until you hear the Apple chime three times. Once it loads up, repair permisisons. Maybe that'll sort it.
I had a very strange issue with my Core2 MBP and doing this sorted it. (I couldn't type a capital i if I used the left shift key - everything else worked, and changing keyboard layouts or restarting did nothing - didn't even work for the firmware password)