Vista won't load sometimes after restarting, why?

I've had my new computer for about a week and everything was pretty easy to setup. I've used Vista on my previous amd machine and it never had any problems.

In my new machine (see specs in sig) Vista sometimes will not load after restart. The machine POST's successfully and checks for raid array, then I get a flashing underscore in the top left of the screen for about 10 seconds, after that vista usually loads, but sometimes it doesnt.

I won't have internet to my PC until feb 13th and im not sure if updates will fix this, and I've done the whole vista repair with the install disc.

I have my western digital raptor hooked up to SATA port 1 and a SATA dvd drive hooked up to SATA port 2. Boot device priority is set to the hard drive first.

Any ideas? Is my hard drive faulty? I can always try another drive I suppose, I do have one kicking around.

Thanks for any help!