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

PDF viewer for RIM BlackBerry

CrackBerry people recommend BeamBerry

... www.cerience.com/products/reader/ or Premium Edition of Documents...

say people from BlackBerry Support Forum

BlackBerry Date/Time Source

BlackBerry Date/Time Source Explained

1. Set it to BlackBerry (the default), which gathers the information from the BlackBerry network, i.e. the RIM NOC.

2. Set it to Network, which gathers the information from the wireless carrier network, whether AT&T, T-Mobile, Verizon, Rogers, O2, Vodafone, etc.

3. Set if to Off, which does not gather any info. You set it and maintain it yourself.

Explanation: BB's Implementation of Time Zones

...this post to elaborate on the Blackberry FAQ, cited below, and to offer a real life example of how the Rim technique works. I hope it will clear up some of the confusion around this topic...

Date/Time and Time Zone Settings: BEWARE!

Network: Your phone time setting is synchronized with your wireless provider’s network time setting. That is the local time of the cell tower your phone is currently connected to wirelessly.

BlackBerry: Your phone time setting is synchronized with the BlackBerry network’s time setting. I guess that RIM has servers all over the world that know the time where they are.

Off: No external time source is used to synchronize your phone time setting.