I was having some serious issues when uploading my project to the Leonardo. One day everything was uploading nice and smoothly, the other (and after some code edits) I was forced to press the reset button or it just wouldn't go through. After breaking my head for several hours, reburning the bootloader, changing computers, USB cables, ... I tried uploading a basic arduino example (with a reset press), tried it again without the press, and it just went on normally. So I went back to my code, disabled the SimpleTimer library (which was one of the latest additions I made) and it uploaded without a problem. I dug into the SimpleTimer lib, and after changing the MAX_TIMERS to 8 instead of 10, the program uploads perfectly.
Does anyone have a clue why it's working with a smaller max timer value? It's not really an issue anymore (for now) but I'd like to understand why it didn't work before. It's probably worth noting I'm also using millis() in the rest of my code as I suspect it has something to do with too many timers being used.
Link to the SimpleTimer library http://playground.arduino.cc/Code/SimpleTimer
Thought it was worth the share! Kevin