Large print failed half way through... TWICE

I was printing the T-800 Terminator skull as a fathers day present and when it got about half way through the printer started to slow down to a crawl and was only moving once every few seconds. The first time it happened I thought the printer board overheated. When I printed it again and the same thing happened at the same spot I knew that it was probably Repetier (Mac) that was the issue. Anyone know why this happened?

Happy Fathers Day everyone