When I wanted to make ftf using flashtool from SUS (Sony Update Service) it got to about 75% and stopped.
Tried again and again and again, they all stop at the same spot.
Then I wnet to flashtool.net and found a new version of flashtool so I updated it and everything went well.
Just update it to the latest version.
Don't forget to hit the THANKS button!
If I helped.