This Happened to me and I'm not sure why if I'm honest i did several steps so i'm not sure which one worked
1- i turned both my radio and wifi off for 1minute
(Menu >>> Manage Connections>>>Turn All Connections Off)
2- I Performed a Soft Reset
(Took Battery out of phone while still on and replaced it)
3- I Deleted APP World and Then Re-installed it
(Menu>>options>>>advance options>>applications>>*find BlackberryAppworld*>>menu>>delete) Re Download Link
Nope. I did lose the top 25 new app section the other day and had to reset the app world to get it back. I'd try to reset the app world first before trying to delete and reinstall the app.
Go into the app world and press R,S,T while holding down the shift key. It will take a min or two for it to start the app over, but you should be good to go once it does.
Posted from my CrackBerry at wapforums.crackberry.com