HT3777: Boot Camp 3.0, Mac OS X 10.6: Frequently asked questionsLearn about Boot Camp 3.0, Mac OS X 10.6: Frequently asked questions
Disconnect all external devices.
If you are pressing C when powering up and booting and if the installation DVD is booting as expected, and if you don't see a disk to install Mac OS X 10.6 Snow Leopard on within the installation, then the system probably has a hardware problem with the disk.
This assumes that the DVD installation disk you're using is the Mac OS X 10.6 Snow Leopard disk that came with this computer, or that this is a new enough retail disk and particularly a retail disk that has a Mac OS X 10.6 version appropriate for your MacBook Pro (HT1159) model.
You can try using Disk Utility from the Utilities menu (second screen of the installation), and see if that can find a disk, and you can ask Disk Utility to erase that. (That will overwrite the contents of the target disk.)
Given your symptoms, a failed disk or I/O-related hardware can certainly be the trigger. Failed hardware would require a hardware repair, and possibly including a disk swap.