Well, I won't lie, that is strange. How often does that happen? If it happens enough then what I would try to do is unplug one device at a time and restart your computer.
However is sounds like Mac OSX is to fault. That could explain all of the symtoms your getting. I mean, it seems to forget your resolution settings, your background settings your new profile, And sometimes it fails to boot. I would say that unplug one device at a time and see if that doesn't help, if it doesn't then try reinstalling OSX
P.S. Just thought of one more thing. Test your ram.