OK no amount of uninstall and reinstall fixed the issue until... I downloaded one of the GPU driver utilities from a popular gaming enthusiast site. Guru 3d DDU. I uninstalled like normal and restarted. The utility then asked me to boot in safe mode to remove everything. I did so. After I rebooted and ran the util in safe mode. I then rebooted to normal mode and went about installing 15.7.1 drivers. After another reboot I tested out streaming and it worked great! So if anyone is having the xbox app crash on stream start this fixed my issue.