list the files on your kindle
find /media/Kindle (or whatever)
then delete the one that has bogus bytes in its filename.
And if you cannot find the file by inspecting the list, use this one-liner
Code:
calibre-debug -c "from calibre import walk; files = [f.decode('utf-8', 'replace') for f in walk(b'/media/Kindle')]; print b'\n'.join(f.encode('utf-8') for f in files if u'\ufffd' in f)"
Replace /media/Kindle above with the path to your kindle.