I have Leopard 10.5.7 and I am upgrading to Snow Leopard 10.6. Here's what happens: 1. Insert disk 2. Click Install (Install begins and progress meter starts). 3. After about 20 minutes, progress meter reads "Time Remaining 46 minutes". 4. suddenly, progress meter fills in completely with blue and white "barber pole" style fill. Still reads "46 minutes remaining". 5. Computer reboots. 6. Computer hangs on reboot (I let this run for 3 hours before I gave up). 7. Powered down computer. 8. Turned computer back on pressing F12 to eject the disk. 9. Computer boots normal. 10. Check Apple > About this Mac 11. Still reads 10.5.7. BTW, I have tried this 3 times and it behaves the same. Any advice? Just as a side note, I don't hear the DVD disk spinning fast or anything like that.