Cycling re-boot on my mac mini

Question

My Mac Mini has gone into a cycle of constant re-boots. I've tried the following to fix this:
- Held down shift key to get into single mode (Ignores me)
- Held down 'c' to boot from install disk - tries, then ejects install disk - install disk mounts OK on my macbook pro
- Held down shift to eject install disk (ignores me)
- Held down 'T' for it to be come a mountable disk - this works. I've done a disk repair with disk utility and there are no disk errors. Everything looks OK on the disk.
- Disconnected all USB drives [three of them were 'locked', but the 'chflags nouchg /Volumes/{name}' command seems to unlock them OK.
What can be going on? I can't see why it won't boot from the install disk, or why it is in this constant cycle. What I wanted to do was a non-destructive re-install and re-upgrade to get back to normal, but, without it booting from the Install disk I have a problem!
Is there any way I can do an update and install from my Macbook Pro onto it?

Answer 1

Sorry - just a rider to the previous question.
My suspicion (since everything else looks fine) is that there might be either a corruption of the boot sectors or some permissions problem - I think the latter because it seems to get further than just the first boot since it spends time with the white apple showing and the busy icon below it before re-booting.
Is there a way to repair permissions with Disk Utility on a remote disk, apart from booting from the DVD - because I can't, of course, boot from the DVD?
Of course the worse interpretation is that there's some fundamental hardware flaw preventing booting from both the disk and the DVD. How would I establish that??