Currently Being ModeratedNov 19, 2012 9:08 PM (in response to CPJB)
Try this instead:
Boot Using OPTION key:
1. Restart the computer.
2. Immediately after the chime press and hold down the "OPTION" key.
3. Release the key when the boot manager appears.
4. Select the disk icon of the Snow Leopard DVD.
5. Click on the arrow button below the icon.
Currently Being ModeratedNov 19, 2012 9:18 PM (in response to Kappy)
Tried that, same story. Also tried selecting the DVD drive in Preferences as the start up disc. I can hear the disc spinning but I can't get past the "click to restart and install OS X.6.3" page.
Currently Being ModeratedNov 19, 2012 9:31 PM (in response to CPJB)
Oops. I confused the option and command keys. When I restart with the option ket the boot manager appears, but the only image there is of the HD. No snow leopard, or DVD drive.
Currently Being ModeratedNov 20, 2012 9:28 AM (in response to CPJB)
Then your external drive is not recognized as being bootable or your Snow Leopard DVD is defective. From where did you get the DVD?
Currently Being ModeratedNov 20, 2012 5:49 PM (in response to Kappy)
OK, so I was sucessful in completing the upgrade, but I am still not sure why it worked, and I thought I would post here both for closure and in case someone else has a similar problem, or an insight into what happened. When the computer restarted itself, I would get stuck in the aforementioned loop regardless of whether or not I selected the external DVD drive as the start up disc, or held the option key down after the chime to get to the boot manager. At last I just shut down the computer with the power button. When I turned the power back on, the system booted up from the disc in the external DVD drive and I completed the upgrade. I'm not sure why that would happen.
I bought the Snow Leopard install disc from the apple store.