This may help some people who have the E18 error. I do not recommend trying the online guide for repairing it yourself use only at your own risk.
First, try hooking your camera up to the TV with the included A/V cable. Rumor has it that this resets the E18 error!
Second, try compressed air. With a fine tip blow off gun and dry compressed air (20 lbs) set the tip between the lens turret and the camera body and turn on the air while moving the tip around the lens. It should remove all sand and dust. Turn the camera on and it should function fine.
If that doesn't work, there's an online guide for repairing it yourself (only worth trying if your camera is no longer under warranty).