[quote=logicluvva]I upgraded to Logic X and had the same problem at first. It turned out that it was to do with me using Automap. I don't know if you are using a similar set-up. All I did was to go into Preferences for Automap and I checked the box "Use Logic 9 64Bit Plug-in Friendly Audio Units ". I do have only one AU that fails now but I hope to sort that out.[/quote] Thanks, this solved my problem! Automap was the one causing it for me.