FWIW, I too had a problem at first with the Latin EZX pack. After upgrading to 1.4.x EZ Drummer 1 I was still getting this error. After reading this thread and doing a little looking around I discovered that I only installed the 64bit upgrade as I try to keep a clean 64 bit install of everything. Well, curiosity got the better of me and I also started the 32 bit installer for 1.4.x and lo and behold the Latin EZX pack intalled without a hitch. Looks like the installer for the EZX only hunts the registry for the 32 bit version. So make sure you have the 32 bit upgrade to 1.4.x before trying to install any EZX pack. Hope this helps someone in the future.
