Since the release of Pokemon GO was very recent, it is not a perfect game at the moment. It still has some missing features and bugs, such as freezing the Pokéball during a fight with a Pokémon with a high CP (Battle Points) level.
While we wait for Niantic to fix this, there is a solution you need to know to avoid wasting your precious Pokeballs. You have to be careful with the launcher, photo and bag icons still on the Pokémon capture screen. Otherwise, after starting your Pokeball, you will see it freezing.
You should wait a minute and then try throwing the Pokeball not directly at the Pokémon. Instead, you can throw it in an empty space, and then if the launcher icons, photos and bags reappear, you can safely throw your Pokeball to catch the Pokémon.
