Safe Mode = Wet Phone
Just a quick note for anyone who runs into the variation of this problem that I had today.
Using my Nexus S today in the rain. Phone got wet. Specifically, damp got into both the Power button and the Volume rocker.
The result was when the phone was restarted (after I removed the battery and dried it out) it came up in Safe Mode.
Which is how I wound up here.
(Minor site quibble: in the course of registering here and making this ONE post, I've been subjected to FOUR captchas. I like sharing information, but this is really WAY more nuisance than is worth it for me.)