Can't boot from DVD or external HD... anyone experienced this?

As the title says, I cannot boot my mid 2010 MBP 15" i7 from the install disc, a snow leopard DVD, or even from an external hard drive imaged with the snow leopard disc.

I originally discovered the problem when I ran a verify disk and was given errors. It told me it couldn't be fixed unless I started from the install disc. After a ton of failed attempts (after pressing the C key.. you just see the grey screen with the Apple, but it never goes anywhere) I started my computer, connected by firewire to my girlfriends in target disk mode and fixed the drive that way. I thought this might correct the problem but still no luck.

I have no need to boot from the disc immediately now, but should I ever want to re-install in the future, I'm going to need to be able to do this. Anyone have any idea what the problem might be?

Thanks in advance!

I did do that

The problem is, that even after doing that, I still cannot boot from DVD, or external HD. I'm trying to figure out what might be causing that problem.

Thanks

spinnerlys said:

Do you have another Mac with Firewire?
If so, boot the MBP into Target Disk Mode and connect it to the other Mac and see, if you can repair it via Disk Utility running on the other Mac.

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