I could never figure out why I could not safely remove an external USB drive that I connected to my computer. It would always give me an error. I found this cool program USB Safely Remove that will tell you what program process is locking the drive. It is ShadowProtectSvc. I use ShadowProtect to backup my computer and have for a long time now. I don't backup to the USB drive but to an internal hard drive.
I wonder why ShadowProtect automatically grabs a hold of any USB drive connected to the system? Anyone else experience this issue?