@Sluijsens I found the solution: I renamed the "xa_validate.xpl" that is in win_x64 to "_xa_validate.xpl". I then copy pasted the "xa_validate.xpl" that is in the mac_x64 folder in the xa_validate folder in the plugins folder of the "IXEG 737 Classic Plus" folder and BAM it works: no more CTD! (I also installed the latest Xplane 12 beta though before I copy pasted the "xa_validate.xpl" file from the mac_x64 into the win_x64 the latest Xplane 12 beta did also CTD with the IXEG 737 Classic Plus. WOW! Works now! Cheers, Clément