Wow, I was pulling my hair out over this ! Even though I had participated in beta testing of ADD 10 and it had worked flawlessly, for some reason I can't understand, ADD 10 stopped detecting my two external USB drives. I tried shutting the drives off, uninstalling them (in all of their instances, also hidden) from the device manager, then rebooting, then turning the USB drives on to re-detect and none of it fixed my problem. I even downloaded and installed the latest SnapAPI drivers (http://download.acronis.com/support/SnapAPI_l_s_e.exe) -- no dice. THEN, after "getting intimate" with the forum search function, I found THIS thread: https://www.wilderssecurity.com/showthread.php?t=93596 I did part of what Alexey Popov suggested to llesau in post #6, i.e.: VOILA ! ADD 10 is now detecting all drives, including my external USBs perfectly ! I'm no expert and I know no more now than I did earlier what the root cause of my problem was. HOWEVER, I post this here because it was posted in the "Acronis True Image Product Line" sub-forum and thought this potential solution/workaround should be more readily visible to ADD users. I hope this is helpful for someone. P.S. I did this while running Windows XP SP2 as an operating system. Not sure how backwardly applicable this is.