If you get an App Error 200 problem on your device, you might need to completely re-initialize your Blackberry. Here is how to do it:

1. Connect the BlackBerry smartphone to the computer.
2. Open BlackBerry Desktop Manager.
3. Double-click Application Loader. The Application Loader Wizard appears. You may need to unplug and re-attach the USB cable to the BlackBerry smartphone at this point for it to be recognized by Application Loader.
4. Click Next.
5. Choose the port that the BlackBerry smartphone is connected to and click Next.
6. If prompted, type the BlackBerry smartphone password and click Next.
7. The Device Application Selection screen appears. Select the applications to be loaded onto your BlackBerry smartphone.
8. If the Device Backup screen appears, choose whether or not to automatically back up the BlackBerry smartphone. Click Next.
9. Click Next. The Completing the Application Wizard screen appears, displaying all the software that will be loaded to your BlackBerry smartphone.
10. Click the Advanced button and make sure that Erase all application data and Erase all currently installed applications are both selected. Note: If the Application Loader is not able to access all of the BlackBerry smartphone data, then both Erase all application data and Erase all currently installed applications will be grayed out.
11. Click Next, and then click Next again.
12. Click Finish. The BlackBerry Device Software is now loaded on the BlackBerry smartphone. Do not disconnect the BlackBerry smartphone until the process has completed.

If this does not work, then you might want to try the following:

1. Pull the battery and LEAVE IT OUT
2. Open the Blackberry Desktop Manager
3. Click on Application Loader and choose Update Software
4. Connect your Blackberry with the battery still OUT
5. If prompted, enter your password/pin
6. If multiple OS's are listed, choose the one with preferred next to it
7. Allow the update to run without the battery
8. When it says Waiting for initialization, it will attempt to reboot. At this point you will need to insert your battery or it will show the battery icon with the red line through it. If this icon shows, simply insert your battery and the phone will reboot again
9. Allow the software to continue the update

(taken from http://www.blackberryforums.com.au/forums/blackberry-9000-smartphone-discussion/4117-please-help-app-error-200-a.html)