Nick, sorry to hear of your problems.
Usually when any of Photosynth's apps close without finishing, it means that your computer (mobile or otherwise) ran out of RAM (short term memory). The only way to avoid this on a phone is to close all other open apps. On a desktop or laptop, you can always buy more RAM and install it and then try again.
I don't know what to tell you about your interactive panoramas disappearing. The input shots captured during the capture process are proprietary files belonging to the Photosynth app - not saved in the camera roll where you could sync them off the phone with Zune. What that means is that if you uninstall the Photosynth mobile panorama app (on WinPhone or iOS), all of that app's settings and temporary files are deleted with the app, so if you tried uninstalling and reinstalling your mobile app, you will have deleted your interactive panos (or their ingredients).