I'm trying to install 10.5 and 10.6 on an external drive for testing software (on a new 11' MacBook) and found that both the disks are not working. Basically when I try to restart the Mac using either of the disks the Mac hangs on the gray screen or in the case of 10.6 it hangs then gives the notice I need to restart my Mac. These both worked in the past and the only notable thing I have done since then is installed 10.7 on a partition. I would delete the partition but it gives an error I need a newer version of the OS to do this. Another thread said I could restart on the 10.6 disk to delete the partition but this isn't an option now. Does anyone have ideas how to troubleshoot this? If anyone thinks it's related to the 10.7 partition I could install it onto an external drive then boot from that to delete the partition but I'm not sure that's even related. Thanks!