You can install our site as a web app on your iOS device by utilizing the Add to Home Screen feature in Safari. Please see this thread for more details on this.
Note: This feature currently requires accessing the site using the built-in Safari browser.
Normally the solution is what you did. Reboot it.
If it occurs really frequently, I would bring it up to the SC. Not sure what they would do to fix it.
Mine freezes once in a while while trying to use the browser, and rarely when using NAV.