Version 3.1 of Quest Pack has been released to circumvent a crash which may affect certain configurations of BG2, notably the GOG version. This problem manifested itself in the game crashing if Quet Pack's Creature Enhancements were installed and the player encountered a Fire or Ice Salamander. Vanilla BG2 and BG2: EE do not appear to be affected (but vanilla BG2 could obviously be made susceptible if the right tweaks were made to it).
If you are concerned this problem may affect you, there is a hotfix available here
which can be installed on top of Quest Pack v3 to solve it. This hotfix is not needed for Quest Pack v3.1.