Mods make the game so much more interesting but the problem is, The Sims 3 wasn’t coded to be mod friendly.  It seems that those who have mods are more acceptable to experience issues than those with a mod-free clean game.  And you know what, EA can’t really be blamed for that as it’s not their responsibility to make sure the patches work with mods.  Would it be nice, yes it would…but they are only responsible for their own content.

I run a mod-free game and so far, with the 1.6.6 patch did not experience any issues.  Of course, there is still a number of those who also run a mod-free game and still get screwed…so I am not sure what the culprit is to be exact.

Anyhow, with World Adventures I think mods will now be stored in a different folder according to SimGuru_BGY_11:

Before World Adventures, the Mods folder and file Resource.cfg were placed in the following directory:
C/ProgramFiles/ElectronicArts/TheSims3 or go to the directory you installed to your game.
WA When installed it created a new folder under:
C/Programfiles/ElectronicArts/TheSims3WorldAdventures.
This is where you need to move your Mods folder and file Resource.cfg. to C/ProgramFiles/ElectronicArts/TheSims3WorldAdventures
You can move the Mods folder and Resource.cfg by right-clicking, selecting Cut, then Paste into the appropriate directory.
SimGuru_BGY_11

Thanks to Sims 3 Nieuws for reporting the tip.