Yesterday I updated my Apple iPhone to iOS 4.3.3 (no, it is not jailbreaked). After that I noticed that none of the installed apps run any more. Of course the built-in apps ran fine (like Maps, App Store, Calendar, Mail, Messages, Clock, Contacts, iTunes, Calculator, YouTube …). But none of the custom installed apps (I tried Facebook, WhatsApp, Amazon, eBay and at least every other app) – they just start, seem to run shortly (not even a second) and then the phone will return to the desktop, homescreen or whatever you call it.
Rebooting the phone didn’t fix the issue… But then, today, the problem was solved by simply installing all updates available in appstore. I don’t know if it was just enough logging in to appstore or if the updates where really necessary. Since there were only two updates available but dozens of apps that were not running, I think just logging in did the trick.

If you are experiencing the same issue I hope that will do it for you as well.

Update: If this did not work for you, for example if you do not have any apps that have updates available, you can simply download any free app from the appstore. This will also require a login and finally fix this issue.
Now that Apples iOS 4.3.5 is out this bug seems to be fixed on iPhones and iPods. All phones I updated to iOS 4.3.4 and iOS 4.3.5 worked just fine…

Update 2: When commenting on this post, could you please leave a notice from what iOS version you came from and what version you updated to? That would be great!

Update 3: This problem seems to be still present when updating from iOS versions prior to 4.3.3 to Apple iOS 5. Again, the steps mentioned above will fix it in most cases…