Unknown Error Occurred

So I started downloading a few days ago.  I had already bought and installed the base game, world adventures, ambitions, late night, generations, pets, and supernatural.  I downloaded and installed all stuff packs, showtime, seasons, university life, and island paradise.  It wasn't working, even after installing the fix, so after a day and a half of downloading and installing, I deleted everything and started over.  I had every single thing installed, except High End Loft Stuff, which wasn't working.  So I played the sims for a while and it was glorious, everything was working perfectly, then it unexpectedly quit, and I don't know what went wrong.  The next time I tried to open it, it says "Unknown error occurred" without even showing the welcome page that has the play button and the downloads and installed content and whatnot.  I installed High End Loft Stuff (sometimes installing a new game would suddenly make everything work) but got the same results, so deleted High End Loft, then started going backwards with the most recent things downloaded, even though they had been working.  I deleted Outdoor Living and Katy Perry also, to no avail.  So, here I am.
When deleting something, since there was no uninstall option on the ones I had downloaded, I deleted both the installed alias, the readme, and went to "Show Original" and deleted that as well.

Go to my Computer, then Install/Uninstall programs.
Do your game show up there?

I'm on a Mac, so no "My Computer"
I actually installed all of my Sims games on an external hard drive, due to the fact I have little extra space on my computer.  Even with the games all installed in an applications folder I have on the external, it runs just fine.  My Documents/Electronic Arts/The Sims 3 folder is on my main hard drive, not the external.  This has not caused any problems playing the game, just letting you know where everything is.