"File not found" but is there

My library lives on an external drive. I put my computer into energy save mode overnight and this morning the files are shown as missing.

image

They are there of course and playable e.g. in WinAmp. How can I make Lexicon to recognise these again? I exited Lexicon and also killed the worker process, but no help.

OK, dropped the files again from Windows Explorer and Lexicon recognises them again