[Alan Anderson]

Did you add the appropriate code to the interrupt service routine before trying to run the program? It sounds like you called the initialization routine to set up the interrupts, but you haven't put in the part that actually handles them.

If an interrupt occurs but the service routine doesn't acknowledge it, it will continue to interrupt the program constantly and not let the normal code run. If the code doesn't get around to communicating with the master processor, it will be considered a code error and the red light will come on.

The moral of the story is: don't try to use half-entered code. Follow the directions to the end.