Thanks for the tip. I would not have thought to disable the interrupt to access data like that. I suppose the 'counter' in you example is an arbitrary variable or is there something special about the 'counter' string in the arduino IDE? I also have never heard that the cpu can buffer 1 interrupt before. Is there any documentation that explains more about this? I did search but didn't come up with much.
Edit: I suppose declaring the 'counter' variable as volatile only removes the need to turn the interrups of and on for the variable to be read if it is a single byte variable.