Take out all your mods and test your game to see if it works, then replace them one at time to see which ones work. That's the best suggestion I can give. With new EPs it's always best to make sure (from the mod creator) if they are compatible with the new EP and/or wait for updated versions to be released.
one at a time can take a LONG time if, like me you are a download whore.... So here is another thing to do.
Go to your desk top make a folder called mods1 and put 1/2 the mods in there.
Now make a Folder called Mods2 and Put the other 1/2 in there..
Now do this....
open your MY DOCUMENTS\Electronic Arts\The Sims 3\ folder. Inside will be a number of cache files: Delete them ALL.... (no this will not brake the game)
* CasPartCache.package
* compositorCache.package
* scriptCache.package
* simCompositorCache.package
Now Put 1/2 the files BACK in to your game and start the game..... If it starts GREAT! Take that folder out and rename it WORKING! Now 1/2 Mods2 again and repeat what you just did. you will end up finding the "bad" seed and weed it out. I once did this with 18gigs of DL.... YES it takes a long time.... YES it is a PAIN IN THE (insert husbands name here) but it will find the bad mod/s that are making things not work right.
Hope this helps :