Option and C keys won't work after startup

Thanks, BDAqua. Followed the instructions and reset the SMC. Then repeated all the steps I listed above. Still no-go. I wonder if it is a keyboard issue. I notice that booting up using wirelss keyboards can be troublesome, and my wired keyboard is a mac board but it is now ten years old - although the option key works fine with it on my old Mac G4.

Thanks, ds store, I think you may have the answer. My Mac Mini came with Lion pre-installed. I am assuming that it has a pre-set firmware password, which blocks the keys I wish to use for booting from disks. It seems that I can access and disable the password via Lion Recovery which will give me access to the firmware password utility via utilities. My question is, can I simply use Lion Recovery to access this, then come out of Recovery and boot up as normal?

Thanks.

That didn't work but then I noticed that you can boot up an external disk via Startup Disk in systems prefernces. so I loaded up Drive Genius 3, selected it as the statup disk to run once and pressed restart. It restarted and ran for a few seconds but then just stopped. Now, the only way I can get back to the internal HD is via the disk manager and the option key on resstart - and of course my option key doesn't work! So it's off to the local Apple Store.

The Apple Store was an interesting experience - in Spain, that is. It took three people to solve my problem. The first problem was that they were unable to find a mains cable for a Mac Mini - in fact they viewed the Mac Mini as though it had just dropped from an alien spaceship. I was then given an appointment in the Genius Bar and passed to a person who purported to know about them and who spoke tolerable English (better than my Spanish!). We did communicate and he did understand my problem but, after spending fifteen minutes looking for suitable gear in the form of a screen, a mouse and a keyboard (wouldn't you think this would all be ready to go?), he set it all up and felt that it might be the hard drive or a RAM problem. I explained that it had been working perfectly just twelve hours ago until I made my foolish boob. He then called a colleague who spoke excellent English, looked at the scree, listened to the HD, unplugged everything, unscrewed the base, took out a memory card, put back the base, plugged everything in and off we went. That took two minutes and now I;ve seen him do it, I would have a go if the same problem arose again. Just be careful taking off and replacing the base and remember to replace the ram after you've got it working.

Thanks for the two of you who gave me advice. I hope the above is useful to others.

Sunnyjohn