Has it finished redownlading all your apps? This is when I've seen this, especially when some apps get stuck in some kind of loop and their download keeps restarting.
Had the same problem from Beta 1 to Beta 2.
"AirServer" app wasn't able to download so I had to plug to my computer and manually "install" this app.
Once that done, no more problem.
Check for an app that begins to download but won't complete.