xiiMary Please read the "Installation" section of How to Use Mods and CC. You can't leave *any* compressed files in - not rar, not zip etc.
If you moved CC onto an external drive at some point, you might have corrupted files depending on the drive formatting. You can't uncorrupt them; you need to redownload them.
To do a strong test of your general installation setup, do this:
- Rename the Mods folder (I do something like "MODS OLD" so it's clearly different in a search)
- Delete the file called localthumbcache
- Start the game and exit
- Download a new CC item and install the .package file in the Mods folder
- Start the game again
