boeing247 wrote on Jan 31^st, 2013 at 12:31am:

I too am having the issue with VNAV causing a rapid descent upon engaging, but I recall that someone (I believe it was Mark) had found a temporary work-around to get VNAV to properly engage until the next SP. What was the process, and does VNAV otherwise work in the current version? Thanks!

Yes, there is a fix that makes the FMC revert from VNAV DES to VNAV CLB as it should be. But FMS-speed control in VNAV (both CLB and DES) is screwed up, too, in v1.0.

So I changed my mind and went to FLCH, too. I wouldn't use V/S, because there's no speed protection in that mode.