Four days ago (6/21/11):
Yamaha released Tyros 4 OS Update Version 1.03 rocker

Here's what's included:

-Fixed a problem in which the "Next" button would disappear from the Normal View when changing the Style Selection display to List View and exiting,
then entering the Style Selection display again and finally returning to Normal View.

-Fixed a problem in certain Styles when re-selecting the Voice for RHY1 and/or RHY2 and saving the Style in Style Creator,
the volume balance etc would change during playback.