Thanks for you comment.
No volumes without letters.
I am using DP 9.01.
All the files reported have strange names, first two letters of the name are replaces with ~$, for instance, bugInDP.docx is shown as ~$gInDP.docx. This suggest that they are lock files created by MS Office when you open the original file. It appears on random files, todays backup has shown another two files. It seems like those files were present at some point during backup but were changed/deleted during backup course. But Volume Shadow Copy should provide consistent look of the filesystme in point of time. Is this another bug when async reading is ON? OB2NOTREEWALK=1
Kind regards, Jan