One of my programmes, which asks if backup is required before exiting, has suddenly refused to backup to an 8Gb flashdrive with the message that there is insufficient space and that I must I insert a second disk. The flashdrive is showing 6.8Gb free space while the programme only requires 31Mb. I have tried using a different flashdrive, but to no avail. Copying the programme data to the flashdrives using highlight and copy gives no problems. Any suggestions as to what is causing the backup refusal?