Try changing the hotkey for quick save/load; someone else had problems with it, and found that made it more reliable.
What problems are you having with the saves which do not work?
Have you tried backing up your saved games, then un-installing and re-installing Divinity?
See
Troubleshooting Tips (& manual install procedure)Neither the cat in the castle or the one in Aleroth will turn hostile, or even care that other cats have.
