Okay, so this isn't the first time I am having this issue. When i am trying to install CC the pop up window instead of the sim plumbob thing it is all black, and says "Sims 3 is not responding" I have already deleted all my downloads off the launcher, I have completely deleted the mods folder and re-installed it along with the nraas content i use. I did everything exactly like I did last time this happened (and i was able to fix it then) ....only now its STILL not working. I don't know what else to do, it was working just fine earlier today and I was able to download some CC, and now nothing. No matter what I do it wont work anymore. I cant even Uninstall content (trying to uninstall a horse) it crashes trying to do that too.

Some players have reported that this happens to them much less often if they pull their Mods folder out, leave it out, and empty the five cache files in the game folder before trying to work with the Launcher that way. Then, of course, they put their Mods folder with its contents back in when finished.

There is no rhyme or reason for the way the Launcher behaves. Nothing short of an Exorcism will fix it.

In addition to the tip @igazor posted here are a few more tips that have worked for me:

Load the game and open the Launcher at the main screen where you select the town to play. Optional if you don't have much RAM to spare: exit the game and clean out those miserable .temp files in the DCCache folder. This will not work for uninstalling.

Many of us are seeing EA script errors when loading: just accept to keep them running and hit the X in the window to close it. There is usually two of those notices and if you have uninstalled Origin as I have a notice shows up the game can not connect to origin. Just click okay.

I tried this and it worked for me: used my mouse to slide the "Sims 3 is not responding" notice away from the Launcher window and proceed with whatever you were doing.

Adding to barbarat's hints: Have the Sims 3 play disc (Your most recently released EP) in the drive when you try to load the Launcher. It should not need it. It usually doesn't. But sometimes it seems to want to give the disc a little attention.

I have had this happen almost every time I use the launcher to install things. I just leave it alone and play solitaire or something until it finally kicks in and does it's thing. Sometimes it takes awhile but it normally works if you have the patience to wait it out.

I've had this happen when installing all of the worlds I have at once. Sometimes it can overload the launcher I think. If you want to you can wait and it will /usually/ recover on its own, but if it doesn't try installing only parts of your CC at a time.