So, your SmartBoard isn't working? And you are getting a green blinking light?
The most likely culprit is that when your hard drive goes to sleep it breaks the connection with your smartboard. The only way to make it work in this case is to restart the computer.
This information is from SmartTech. Apparently there is a problem with Mac OS 10.6.3 which causes this problem.
You can also avoid it by unplugging your SmartBoard from your computer when you are not using it, rather than leaving it plugged in all day. Also always leaving the power to your computer plugged in at all times when you are using the SmartBoard.