We pushed a major back end hardware update to the website this evening. It is possible you will need to clear the app cache on your phone before you can view topics. To clear the app cache do the following:
1) open the app, tap the menu > settings > clear cache
2) force close the app (double click your phone's home button, and slide the TT app off of the screen)
3) re-open the app, and log back in using your email address.
We apologize for the trouble. Apple loves to aggressively cache app data to make their devices go faster, and the steps outlined above will get your app working without having to wait for iPhone to clear the cache on it's own.