Now look what I found in the D4 manual "5.9.1. Accessing DIVE mode
The Suunto D4 has three diving modes: AIR mode for diving with standard air only,
NITROX mode for diving with oxygen enriched mixtures, and FREE mode for free
diving. The OFF mode disables the DIVE mode, and allows the TIME mode to be used underwater.
The chosen dive mode is displayed when the DIVE mode is accessed, and
you can toggle between the submodes by pressing the UP/DOWN buttons."
So there is supposed to be an off selection on the dive menus.... I'm cycling through them again.... no off... I wonder if I should take my computer in... software update maybe? glitch?