trying to upgrade to 10.2 from 10.1.5 and it just sits at what i think is an install screen that has an apple in the middle and a small animated circle of lines below it, after it reboots. I updated the firmware to 2.4 ( I have a g4 dp450 ). I've combed apple support and all they say is to check the cd or try a new one. has anyone else had this problem?