@Quadrupel - where did you insert the startup patch in startup.c - that is a VERY busy file - don't want to break it. Also - I'm keeping a copy of the original..
I stuck it in the resetHandler function.
Because, I don't like modifying core files, and until there's a production fix to IntervalTimer, I'm putting the fix into the beginning of setup(). It works, and the appropriate comments identify why it's included in the code.