Jerr, when you try to delete the .ufo files, do you get messages like this?:
Cannot delete file: Access is denied
There has been a sharing violation.
The source or destination file may be in use.
The file is in use by another program or user.
Make sure the disk is not full or write-protected and that the file is not currently in use.
If so, you need a little free program called Unlocker, available here. If it cannot delete the files, there is an option for you to be able to delete them at next reboot. Works with Vista.
Saludos,
Bob.