OK, too little and too late for some, maybe in time for others - don't ever lose your stuff with a naked reboot.
http://androidforums.com/evo-4g-support-troubleshooting/141369-how-fix-froyo.html
And yes, it's an older thread - but - things still get tangled in updates, they always will until they change their update strategy, and bookmarking that thread is a good idea - or - just look for its link in the sticky thread at the top of this sub-forum.
When your phone gets really loopy after one, and working things stop working, try the advice in that thread: backup / reset / restore+check your new config.