Several Cartridges seems to have stopped working in 2.4
"Invalid Cartridge Image" appears when trying to attach i.e. Action Replay cartridge hacked by Triad:
http://csdb.dk/release/?id=3405
tested both x86 and x64 versions on Win7 x64
I just checked. same images works in 2.3
I'm sorry to say, but actually 2.3 had a bug that it accepted them. The headers were incorrect, mostly stating a 32 byte header lengths instead of the correct 64 byte.
I've uploaded the corrected versions to csdb for you, please update your .crt files.