I got err18 with or without mod, I remove cleanly all mod and any plugin shader etc (I got plenty of backup file) and still get err18 when I capture monster, I havent tried killing them yet
I heard ppl get the same error with mod, they said removing mods fix it but doesn't work for me and some other that also don't have any mod, I think it is just unstable new update as usual. Ima try updating or reinstall driver and hope for the best