Unresolved Kernel Trap


Ok, I have a dual usb ibook running osx 10.1. I am getting an unresolved kernel trap error at startup. However, I have found that if I pull the cdrom it startsup and runs just fine. I have tried 2 different cd drives and have the same results with both. I am not familiar with macs, but I have done a ton of reading on these boards the last couple of days, and have tried pulling the ram, the pram reset, and the fsck -y command in single user mode, but to no avail. Any thoughts would be greatly appreciated.