hi guys, i've been all over the internet for this problem but didn't seem to find any solution i am close to giving up. i just got my macbook back from a harddrive replacement because it recently failed on me (but i did backup so i wasn't too sad about it). so now i'm back to a clean os and everything. problem is, they didn't use the tiger install disc that came with my macbook and installed tiger on their own. my macbook is late 2007 model but still on tiger. now i really want to wipe it clean and use my own install disc but it keeps on rejecting my original install grey disks. no matter how much i restart with the C or D or alt key pressed it really won't work. the cd is still in good condition as i've only used it once since i got my macbook. any help? thank you so much in advance.