The usual culprits for Pets-related crashes on non-pets installs of the game are:
- Trees
- Shrubs
- Sofas
- Chairs
- Beds
- Any pet item (pet bed, pet toy, etc.)
- Diagonal roofs
- Rotated floor tiles
In some instances a "stray" is on the lot during export to Sims2Pack and this can cause endless woe for any non-Pets player even if every precaution is taken to make the lot non-Pets friendly. Don't ask me how a stray ends up on a lot that has never been played, but I have seen the pet character files in a few of the lots I have downloaded.
Custom content in the following categories can cause a crash to desktop (CTD) or even a general protection fault (GPF) if the creator has not taken careful measures to make there CC base-game compatible (even clones of base game items):
- Trees
- Shrubs
- Sofas
- Chairs
- Beds
Many mods/hacks have to be made in two versions pre-Pets and for-Pets, depending on the nature of the hack/mod there may need to be a different version for each EP.