If you ever run the product "Black Ice Defender" on any publicly-exposed PC, you will be AMAZED at how frequently there are attacks against IP addresses. IP exploit attacks are a constant, unyeilding barrage against anything that responds to pings that is exposed on the public internet.

For those who haven't tried Black Ice Defender, I highly recommend checking it out. It's a very cool product. It will identify anyone attempting to attack you, identify the type of attack, block the attack, and link you to a detailed description of the type of attack.