You probably have already tried this but I've found that some times if I delete the app, shut down the device (top and home button hold down) then start it up and re download/install it works better than delete then reinstall.I still cant get online with ipad2. Doesnt even get to login page, got it maybe 2 times up to there from 100 trys and 4 or 5 reinstalls :/
Haven't had the problem with ch but this has worked on other apps where reinstall didn't so well. My guess is in those cases something stayed in temporary memory and caused an issue.