I've an IMac mid 2007 (RAM 4GB) with mac os X Mavericks installed; 9-out-of-10 times when I close Firefox (25.0.1 with ABP 2.4 installed), it freezes and I have to do a Force Quit.
Disabling ABP 2.4 i've no problems closing Firefox.
OS X 10.9 - ABP 2.4 on Firefox 25.0.1 - force quit
Re: OS X 10.9 - ABP 2.4 on Firefox 25.0.1 - force quit
As I cannot reproduce this issue with FF 28, i assume it might be fixed. If you encounter it again and can prove a relation to ABP (try to disable), please file a detailed issue at https://issues.adblockplus.org