Just an update. I stopped ExpressCache in Task manager for several weeks, and all of my external hard drives worked correctly and I could eject them. A few days ago I turned ExpressCache back on, and again ExpresCache is constantly accessing the external drives, I cannot eject them. Although everything seems to work ok, the constant drive activity is a concern.
Some have said that ExpressCache does not defrag or cache USB drives. This may be true, but it is certainly doing something with the drives.
Obviously I am not the only person with this problem. It is unfortunate that someone from SanDisk cannot shed some light on this problem.
