Blackberry 8100 error 507please help me fix it

Error 507 means that the operating system on the handheld is missing.

1) Download the latest version of the handheld os from your carrier's web site
2) Execute the downloaded file
3) Locate and delete VENDOR.XML from your PC's C: drive
4) Connect the BB and start Desktop Manager

It should reload now.

Cause The error message indicates that no applications are loaded on the BlackBerry smartphone.

While using the Application Loader tool to install BlackBerry Device Software, existing applications on the BlackBerry smartphone are erased, and new applications are not loaded.

Complete the following steps:

1. Verify that you have the BlackBerry Device Software installed on your computer.
2. If your BlackBerry smartphone is connected to a laptop computer in a docking station, disconnect the laptop computer from the docking station and connect the BlackBerry smartphone directly to the laptop computer.
3. If a third-party program, such as a virus scanner, is using the same communications port (COM port) as BlackBerry® Desktop Manager, close the third-party program to free the COM port for use.
4. If you are using a USB adapter to connect your BlackBerry smartphone to a serial port on your computer, temporarily connect your BlackBerry smartphone to a computer with a USB port.
5. Open BlackBerry Desktop Manager and double-click the Application Loader icon.
6. Use the Application Loader tool to install the BlackBerry Device Software.

Hope this helps :) http://forums.pinstack.com/showthread.php?t=1795