Lot thumbnails/ textures: It has been seen that the low LOD lot textures (what the lot looks like from a distance) can look strange in worlds opened using these methods.
This is just caused by the game messing up some texture files, you can correct it by entering the lot (in EIG or in-game) and editing it slightly by moving a tree or spraying terrain paint. This will cause the lot textures to be recalculated correctly.
Lot names/ sim names being displated in the form World\ Pleasantvalley\ housename:Goth or similar in EA Worlds: This seems to be due to the way in which the sim and lot names are stored- the world file references an STBL rather than storing them as plain text. The only known solutions are to manually edit the names in EIG, or to import the _XML resource from the original EA world to your CAW world, as in this post by Inkantator. (Thanks Inkantator!)
Populated worlds- MODL resource giving an error in S3Pe- This seems to be happening when opening user populated worlds (populated using this method). S3Pe will give an 'Error reading resource' message. To get around this, you could try using the second method as this does not involve S3Pe reading those files.
'Could not open package' error in S3Pe- if you try to open any of the world files that came with the game and you have Vista/ Win7, you may have an error which is caused by the UAC protecting game files. To solve this, copy the world file to your desktop before opening, or else open as read only with S3Pe.