One suggestion, More on the included link to RIM.
View Document
Cause 6
The folder and message databases are corrupt.
Resolution 6
Backup the BlackBerry smartphone data. Then clear the folder and message databases and synchronize, by completing the following steps:
On your computer, connect the BlackBerry smartphone and open BlackBerry Desktop Manager.
Double-click Backup and Restore and click Advanced.
In the Handheld Databases section on the right, select the following databases: Folders, Folder ID, Messages and Purged Messages. Hold the Ctrl key to select more than one at a time.
Click Clear. In the warning dialog box, click OK.
Close both Backup and Restore windows.
Open BlackBerry Desktop Manager and double-click either Intellisync for BlackBerry Enterprise Server version 4.1 and prior, or Synchronize for BlackBerry Enterprise Server version 4.2 and later.
Make sure Reconcile Messages is selected and click Synchronize now.