i upgraded my macbooks hard disk in april after being stuck on a 120 gig hdd for a year and ever since my laptop has started giving me problems.it starts when i boot it in safe mode but when i let it boot normally the apple sign comes then it goes a blue screen comes for sometime then a greyish whit and then a blue again...any suggestions on what could be the problem....i cant reformat my laptop cause the cd drive doesnt work ...earlier i thought the lens was dusty ,i opened and cleaned it but it still doesnt work .....how can i fix this ????i really need the laptop to be fixed and my folks wont let me spend money on it anymore.....