I am experiencing the lot the active sims is on disappears when zooming in or out with World Adventures only not in the base game.
Tracked it down to my custom content in the mods in the EA programs Bin folder.
Once it get over 450mb only. No mater how I choose to reshuffle the content it still does so. The game loads in about five minute and seems happy with all the content.
Graphics setting on high or low makes no difference.
Base game is good without any problems only once I have installed WA.
From my perspective is that the game engine is starving for allocated memory.
Machine specs I have is a 2.8 Quad core, GTX 280 express video card, 8gig of ram and 1 terra bite HDD system Vista 64 which should eat it.
The only way I see myself to get around it is to convert the package format to a Sim3 custom content file as they don't effect it but unable to find a tool anywhere to do so.

This is not a site issue, it's a game issue.

Please post in Game Help. Thread locked.