The 9850 has add some issues with various pre loaded applications and Appworld may be one.
Lets try a removal of the application and new reload.
1) Check and, if installed, remove AppWorld from your BB
KB10040 How to view or remove installed applications on a BlackBerry smartphone
If it requests that you reboot the BB, do so
2) Do a Battery-Pull reboot (power on, remove battery, wait, insert battery, wait), even if redundant to the one you did in step 1.
3) Install (on your BB) a fresh copy of AppWorld Download BlackBerry App World
Again, if it requests to reboot, do so.
4) Do another Battery-Pull reboot