I have run into an unexpected, and unexplainable error in doing a Windows 10 Disaster Recovery.  Did I miss something or do I need to file a support case with Retrospect? Having solved my drive letter issues, I was able to run a Disaster Recovery process.  I'm now running Retrospect 17.5, and using a newly created Disaster Recovery USB.  Retrospect 17.5 allows a USB drive as the Disaster Recovery software media, even if the manual doesn't cover that feature. The procedure notified me that the entire contents of the target drive would be deleted.  (See below).  Then I selected the target drive.  Note that I couldn't use Wizard Mode because my drive letters got shuffled around by the Win PE execution environment.  In Advanced mode, I selected the right drive and partition, using the existing partition names. The procedure then deleted some files and folders in the target partition, but then quit running after about one minute, with an "incomplete" message.  I even ran the DR procedure a second time, with the same result.  I thought that the sessions would be recorded in Retrospect, so I didn't need to do screen photos.  I was wrong.  If someone needs to see screen photos, I will have to repeat this entire process. However, the DR procedure did NOT delete the existing partitions on the target drive, but it did screw things up so that I couldn't boot my system.  To protect against this issue, a while ago I started using the free version of a system-disk oriented utility, Macrium Reflect, also a favorite of the Tenforums cogniscenti.  It doesn't hold a candle to Retrospect, since all it does is back up and restore drive partitions, but it's simple and reliable.  Every time that I have tried to do a Retrospect Disaster Recovery and the my system wouldn't boot, I simply did a partition restore using Reflect.