Blackberry Tasks Duplicate Record Internal Error #4238 Transaction Cancelled

Mobile Platform: Blackberry 8320 v4.5.0.110 (Platform 2.7.0.90)
Mobile Application: Tasks v4.5.0
Wireless Service Provider: AT&T in Brooklyn, NY

Desktop Platform: Windows 2000 Server v5.00.2195 SP4
Desktop Application: Blackberry Desktop Manager v4.2.2.14

Symptoms: Blackberry Tasks synchronization fails with $subj message.
Solution: Eliminate duplicate task records on the Blackberry Device:
1) Show completed tasks.
2) Sort tasks by subject.
3) Locate first group of tasks with the same subjects and remove all of the duplicates.
4) Attempt synchronization again. If the same error occur - repeat step 3).

Other solution that either did not help me or I never tried them:
Internal Error 4238 Transaction Cancelled for Microsoft Outlook
How to delete the Intellisync folder if synchronization is unsuccessful
How to turn on advanced synchronization logging for Intellisync when BlackBerry smartphone synchronization fails // comprehensive tutorial on how to overwhelm yourself with the useless and obscure log messages ;-)
Sync problem with Microsoft Office // personally preferred, but did not help either