boot repair disk not working

[bthom70]

I have a late 2007 20" iMac with stock 320GB drive.
I recently discovered via disc utility and Onyx that there are errors and I should run disk repair at boot.

I am unable to boot to the cd/dvd
I have tried many times to use the C or Option key at boot and it never works, I go to my login screen.

Also single user mode also does not work.

Anything else I can try?

 

[rkaufmann87]

Are you using the ORIGINAL Install Disc that came with the machine in the DVD drive or a Snow Leopard Upgrade Disc to restart from? If you are trying to borrow someone else's Install Disc it won't work because they are machine specific.

Put the disc in the SuperDrive then while holding down the OPTION button restart the computer, it should provide the selection of the DVD to restart from. Choose that and wait, it takes several minutes to boot from a DVD.

 

[bthom70]

I've tried the original Leopard disc and the Snow Leopard Upgrade disc. both do not work.