Problems connecting Macintosh computer via USB to SMART Board iwb: The on-Board LED flashes green, red, green... then stays red.
There are several possible reasons for failure to get a good connection between the SMART Board and a Macintosh computer via USB.

1- Smart Service not starting
2- USB port on computer not delivering sufficient voltage
3- Faulty cable
4- Faulty Board

1/- SMART service:  If you browse to the Applications folder on your hard drive, you will see under SMART software that there is a file called SmartBoardService.  Try starting this while the board is connected, and see if the red light on the pen tray turns to green.  Some of our customers report that this seems to "jump start" the Board recognition, and they have placed a shortcut on their desktops to facilitate. This service should start automatically anyway if the software is correctly installed so if this turns out to be a solution for you then it suggests an underlying installation problem which might best be resolved by reinstalling the software and ensuring relevant privileges are available to you.

2/- USB Port:  The USB port from computers is supposed to supply a steady 5 volts to the USB applicance, and many appliances (including SMART Board) are dependant on this supply.  If the supply dips too low then the SMART Board will not work.  We have found that there are irregularities in practice:  especially with Macs, the USB voltage output on some ports is too low. Try the various ports on the computer; often you will find one which is more reliable than the others.  If this does not work, then the best solution is to buy a powered USB hub, connect this into the computer, and run the SMART Board from this hub.  That way the voltage output can be guaranteed.  These hubs are relatively cheap now (below $40).

3/- Faulty cable:  In the 500 series SMART Board, the board requires a serial (DB9) input.  A special cable is provided to connect to the serial input at the board, and to the computer via USB.  This cable includes an in-line DC voltage adapter.  We have found (again by far more often the case with Macs) that changing the cable can improve the incidence of green light connection.  I think that this is likely again to be a reflection of the USB port output which can be compensated to some extent by a more effective in-cable adapter.

4/- Faulty Board:  I have included this possibility for completeness.  However we have never encounterred this before and so I propose that this is the least likely source of the problem.