Having problems after patch 1.55 and installing Island Paradise?  The main problem posted has been about a black screen showing up and the game not loading.  As always they blame CC and mods, some having removed all their CC and mods to re-download everything!
Do not panic!  It happened to me also and there is a very simple solution.  You will have noticed that you have some new temp files that were added to your DC cache; remove those.  They will be generated back when you use the launcher again!  Those files are EA's way of not having downloads disappear, like with previous patches.  OK, now go into your saved sims folder and move to another folder on your desktop, Save it!  for future reference, since my game did not replace it after I opened and saved the game!
Go to your game bin and make a short-cut of your Sims 3 W application and Voila!, your game will start.  I have tried starting it from the launcher and it worked also, even after the temp dbc from the DC cache were back!; so, apparently the issue is the downloaded sims index, since when I replaced it again, I had the same issue.  So, save it, until someone comes with a fix, since this is just a workaround.   And no if you remove the downloaded sims index from the folder, your saved sims will not disappear.  You will be missing the ones installed via the launcher!  When installing new ones, until this problem finds a better solution, go to create a family and open the sim you downloaded, save it to the bin!  Ok, now your downloaded sims will be saved to your bin without loosing him after removing the downloaded sim index from your saved sims file.