mmm not sure what happen to your USB folder. But pls try this. Download
the software from the David Website, choose to unzip the archive (Not installation, only extraction) then unzip it into a folder named it as the release version (eg.: DAVID_Setup_220.127.116.1198). When done, just copy this folder into your USB key (will be copied near the existing one). Then try again to start the executable file from this latest one folder.
If still don't work... try copy start the software from the downloaded folder ON your computer and leave the key insered into USB port. If again no results, try to copy the original David folder from your key to the desktop and start from your computer, still with the key in the port.
If still don't work, pls ask send an emal directly to the customer service.
Just tests. I had crash problem if I start the updated software from the key, so I use the version on my pc but with the insered key... works.