Sounds odd. Sometimes when you install an expansion you get a message saying that there might be a compatibility issue because the base game is more updated than expected. However this is safe to ignore and the installation is usually fine. Your error sounds different if it is questioning the authenticity of your game. It sounds as though you've already tried some form of uninstalling - did you do a clean uninstall? If not, try it, as it does sometimes resolve installation issues. There is a guide here: http://bluebellflora.com/the-sims-3-on-a-mac/how-to-do-a-clean-uninstall-and-reinstall-on-a-mac/
Then try installing from scratch. First the base game, patch that up to date (1.63), then install the expansion packs in order of release date. You could register all the codes and do the whole lot from Origin, or use a combination of discs and Origin if you prefer. I will paste some Origin info below.
The first thing to check is that your Mac is sufficiently up-to-date to be able to run the Origin client. It requires at least OS X 10.6.8 with an Intel Core 2 Duo processor or better.
To download and install games through Origin:
First install the Origin client for Mac and make sure it is up-to-date. The latest version can be downloaded from here: http://www.dm.origin.com/mac/download
Additional advice on how to download games (thank you Tremayne for this tip):
When downloading from Origin, do NOT use the first install icon. Move your cursor over the game cover and click on the information (letter i) and then click on the install button from there.
For some reason, downloads from Origin frequently become corrupted. Using the i reduces the chance of your download being corrupted. If you have already been unfortunate and have a corrupted download, then it is important to remove all traces of this before trying again, by doing a thorough, clean uninstallation first.
Are you running anti-virus software or any clean-up applications? If so, disable these, as they might be deleting files that Origin needs!
Good luck!
Caspin
