This is an occasional but very aggravating problem that sometimes happens. Sometimes things get corrupt in Blackberry Desktop. Problems can happen if you lose power in the middle of synchronization or other reasons. Computer crash. Etc.

If this happens, and you can no longer sync, you ever get a message "specified Intellisync Configuration invalid" when you attempt to sync your Blackberry in Blackberry Desktop, there's a way to solve this. Sometimes reinstalling Blackberry Desktop doesn't always fix things. However, there's a simple fix.

1. Make sure your Windows Explorer is configured to make hidden files visible.
   
2. Quit all Blackberry software, close all Blackberry-related icons from your system tray too.
   
3. From Windows Explorer or My Computer, go to this folder:
   "C:\Documents And Settings\[YOUR LOGIN]\Application Data\Research In Motion"
   
4. Rename the "Research In Motion" folder into "Research In Motion OLD". (It is usually safe to delete the directory, however, it is safer to rename it instead) If you are unable to rename the directory, reboot your computer into Safe Mode in order to do so.
   
5. Restart your Blackberry Desktop software and try to sync again.
   
6. You may need to reinstall Blackberry Desktop.

Based on information that comes from this RIM Developer Forum thread.

Mark, thank you for the help. I did rename the folder and restarted desktop manager. It stated that "no applications for synchronisation" so I went to Intellisync and configured the PIM. However, the moment I choose an application the OK button blinks out and the screen disappears. Could you please let me know how to proceed? Thank you.