Usually intervals of two to five work when trying to underclock. Then stress test it, then if it fails, lower it again, repeat process until everything is suitable.

Though, it could also be an issue with sufficient wattage going to the graphics card, you could have less than the required. Can you possibly post your specs?

I was told to ask questions about bitcoining here (recommended from another forum), I am new to this whole process and I don't quite understand the whole process of bitcoin mining, other than it is a very slow process.

Does anyone have any links, I have read the wiki page on the main bitcoin page, but I still don't get it.

Thanks.