Start Up Error 'Stop Sign'

I am having a wee bit of a freakout/breakdown right about now. I just tried to reboot my computer and I got a freaky stop sign symbol.

At first the classic Apple showed as per usual... then a circle with a line in the center. It would not boot up. I freaked, unplugged it, and took the battery out. Now I am not sure was is wrong or what to do.

Is this a fix I can do on my own or do I have to get some expensive repair work done?!

Please if someone has seen this or have dealt with this before, give me your advice and knowledge!! I can't live without my computer. My life is on it!!

Thanks so much!!!

What did u do just before the problem appeared? And do u have a back up copy of your HD?

No I was in the process of getting a backup system.

Nothing unusual happened... I was on it all night before and nothing out of the ordinary happened... I didn't download anything. Just checked emails and such.

Any advice??

Do you have the software Install disk that came with the MacBook? If so u could press the power button insert the install disk, hold down C Key and see if it will boot off of the Install disk. If that is Ok then try shutting down and power on and hold down the option key - does it show 2 choices or just the install disk as being available to boot off? I have not seen this before but in your situation i would try those 2 steps to try and see if it is a software issue or a hardware one.

Okay will try. Thanks Collin!

Okay so I did a hardware test and there were no problems. I can't seem to see if its a software problem. Could I get more clarification on that? Because if I reinstall my OS I will lose everything correct?