Sorry for the double post, but have a brief update. I'm unsure of what this means yet, but I installed the base game, opened the launcher and installed all the updates (it took FOREVER).
I just inserted World Adventures to install, and got a "Warning! The Sims 3 Version is more recent than expected."
So... is this okay? I got that notice once before when I tried to install OLS after Showtime, and that was the first time I experienced the disappearing EPs/SPs, so I'm nervous.