I have a Gigabyte GA-7N400-L motherboard and am running Windows XP Pro SP1. Recently, my computer has been crashing (powers off) with no apparent reason. Sometimes I will have the computer on for hours before it crashes, at other times it crashes within minutes of starting up. I believe the motherboard is sending out some type of error code because I hear a low-pitched tone, high-pitched tone, low-pitched tone, high-pitched tone and then the computer crashes. My motherboard manual talks about tones that happen at start-up, but nothing about tones once the computer has gone through the start-up sequence. Any suggestions?