If you're having trouble with the latest Angry Birds Seasons update, first make sure you're connected to the internet (preferably WiFi). Because there's a new level every day, the game needs to connect to the server in order to download the new level.
If you're connected to WiFi and still having trouble, please send a report including information about your device, operating system, and a detailed description of the problem to firstname.lastname@example.org. In some cases, rebooting may fix the issue.
We are currently experiencing an instability issue with a number of first generation iPads running iOS5. We are working on a fix, and this issue will be resolved with an update soon!