I have a MSI K8NGM2-FID motherboard coupled with a AMD Athlon 3700+ and an Antec TPII-550 power supply. The computer crashes at random times in operation, sometimes taking a while to crash, and sometimes crashing right after Windows XP shows the desktop after boot.

The CPU temperature is always in the safe range, usually 30-33 degrees Celsius, and swapping the RAM has not done anything, so the crashes aren't cause by the RAM.

What could be causing this? If the motherboard were fried, would the computer even boot at all? What causes inconsistent crashing of the computer?

After the computer crashes, the LED power indicator blinks about once a second, and the computer does not respond to the power button. This behavior continues until the computer's power supply is completely removed.