It's a bug which has already been identified, and Adobe say it will be fixed in the 4.1 Final.
Laptop: Late 2013 MacBook Pro, 16gb Ram, 512gb SSD, 2 x External HDD
Desktop: i7-930, 12gb RAM, 2 x SDD, 3 x Internal HDD, Win7 Pro 64bit
Cameras: 5D MkIII, 7D, Panasonic DMC-FZ1000
Good to know. Thanks Jim!