When i exported the panorama, stops at 39% and i don't know why ...

Hello, xionMart, 

When you say "exported the panorama", what was the last menu option you chose before the app stops?

If the app is stopping while stitching the panorama, then your phone is probably running out of RAM because other apps are still open. 

If that is the case, try shutting other apps by rebooting your device and then only opening Photosynth's app as described here: 
http://photosynth.net/discussion.aspx?cat=a6bad539-de7d-4a16-8c4d-b143f7d5f984&dis=2dd200e2-f6c6-4735-8078-1ba534bf3953