Hello Mick and RustyGT,
Thanks for the quick replies and the welcome to the forum.
I'll try and respond to both of you with the one post if I can.
Mick, It was actually me who set the password.

I was trying to remove the existing password that I had to put in a few days earlier. When I got to the part about clearing/changing the password, I entered the existing password and hit the enter key at the new password and confirm password fields. Now it wont respond to either. I've tried all sorts of combinations with caps locks, space key, ESC key and anything else that I could think of.
I have the battery out and the power disconnected to make sure that there is nothing keeping it alive. I'll try again tomorrow so hopefully you are right about the time to reset.
I'm guessing that there is a capacitor somewhere on the board holding the charge and there just so happens to be a capacitor just near the CLR_CMOS area of the board, but can't be sure enough of it to take to the board with a soldering iron just yet. Maybe a last resort.
The board was supplied with the computer which I bought from a retailer in Sydney (I'm in Brisbane...forgot to put that in the profile) so I expect that's how it came from GigaByte.
I did find a reference to something similar to my situation elsewhere on this forum somewhere. That's how I found out about it. The other reference was for a different GigaByte board but the main thrust of the thread was how bad their support was and there was no answer of how to reset it.
That mainboard also displayed the symptom of not responding to a known password and also did not have the CLR_CMOS pins. Might be a common bug after all just not rearing it's head very often because most people don't bother using BIOS passwords.
Rusty, I tried your suggestion of "system" but that didn't work either. Nice try though and I am willing to try almost anything at the moment.
Actually, I just noticed something interesting. When it does bootup, there is no activity with the keyboard lights. It normally boots with the NumLock light on though I can't remember if this usually comes on before the password is entered or after.
The keyboard IS responsive because it shows a failed attempt when the ENTER key is hit. When I hit CTRL-ALT-DEL all three lights on the keyboard blink momentarily before it reboots. I don't know if that sheds any light or not...just seemed strange.
Thanks again for the replies fellas, I'm also awaiting a response from the manufacturer and supplier so hopefully some good may come from there.
Steve C