I use U3 USB to run some programs from it. Windows assigned the drive letter. Then I ejected it and unplug it. Then I plug my external hard drive to make the back-up by SyncToy. But SyncToy can't find the drive to do sync. When I check in My Computer, that portable drive is assigned by other letter. Let say, there are C,D,E for Hard Drives then F, G for DVDs' and H,I,J,K for card readers. The portable hard drive assigned as M instead of L. L is assigned to U3 USB drive, even though that was unplug already. Why this is happen and how can I fix that? Thanks.