"Also delete the contents of the My Documents\Electronic Arts\The Sims 3\WorldCaches\ folder. If you do not have a WorldCaches folder or if that folder is empty, don't worry - that's fine."
My own Documents\Electronic Arts\The Sims 3\WorldCaches\ folder has two files in it... and following the instructions, I deleted them.
It was Bad. Very bad.
I can't speak for the PC version, but on the Mac version, Sims 3 requires those files to correctly display hover tags for sims and residences. Removing them makes the names of everything in Riverview look like a system path and file name, rather than the actual name of the sim or location. It may sound minor, but the paths were quite long and sometimes would cut off before you could read the very end to find out who/what you were looking at.
Deleting and reinstalling the neighborhood was a royal pain. Since the neighborhood was only partially there, it wouldn't delete so I went 'round and 'round with EA support to manually delete ALL the Riverview files so I could reinstall the neighborhood.
Just thought I'd mention it in case someone would like to add this to the first post. I'm all for saving people THAT particular headache