Fritz Box 7390 management pages and Telefonbuch

Fritz Box 7390 reliable as VDSL modem since Feb 2012.
Firmware version: 84.05.22
But a lovely obscure gotcha.
Symptom:
The Telephone - Calls page blank. (Calls being Pushed correctly - so just the display)
Also Call Divert pages broken.
Multiple AVM support calls - eventually suggest a Factory Reset.
Perfect! fault cured.
Restored Telephone Book - Fault returns.
Binary chop of the XML telephone book data located a rogue entry with realname 'text' containing an embedded 'newline'
The phone book goes back a long way - Psion . . . Palm . Palm Treo - Android.
then Android app contacts2fritz.

XML Notepad: Find - Search Filter, Text - Use regular expressions - \n
found four more records containing 'newline' - Edited.
Result 450 entry telefonbuch works ok. Calls are displayed and Call Divert works.
Since I queried a fault with BT and the more recent firmwares, CLI is reliable.
7390 now rock solid and CLI 'Withheld' or 'unknown' get Call Divert to an internal answerphone, with a greeting that suggests 'Use 1470'.
Overseas callers have been warned to dial a VoIP number.

I have never heard of this problem before but as a 7390 user I'm very grateful that you took the time to post with a solution to the problem.
Have you come across http://www.fritzforum.com/?