I have built some controllers for fluorescent tubes.
The script is basically just writing high and low to the control pin.
The arduino stalls at random times. Sometimes straight away, sometimes after 10 minutes.
I have tried several minis as well as a duemilanove.
The duemilanove unfreezes when I pull the control pin, so there must be some kind of current rolling back through the circuit. Also, when I set the ons and offs to close, the stalls occur. Sometimes the minis even reboot. I am chasing the blinking on/off effect of the tubes. I am aware of fluorescent lights kicking back dirty when switching them on and off but I thought this circuit would be protecting the arduino.
I am using this schematichttp://www.arduino.cc/playground/uploads/Learning/relays.pdf
I am about to build the master controller which will run 64 tubes, so I really need to understand whats bothering the circuit.