Windows Live Messenger doesn't start

At Midsummer time, Windows Live Messenger conked out and no longer started up.  There was an error message in the application log:

Event Type: Error
Event Source: Windows Live Messenger
Event Category: None
Event ID: 1000
Date: 2010-06-24
Time: 23:17:49
User: N/A
Computer: AOPEN77
Description:
The description for Event ID ( 1000 ) in Source ( Windows Live Messenger ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: msnmsgr.exe; 14.0.8089.726; 4a6ce533; wldcore.dll; 14.0.8089.726; 4a6ce514; 0; 00002ee5.


I downloaded the latest version and installed it, but the result was the same:

Event Type: Error
Event Source: Windows Live Messenger
Event Category: None
Event ID: 1000
Date: 2010-06-29
Time: 21:56:58
User: N/A
Computer: AOPEN77
Description:
The description for Event ID ( 1000 ) in Source ( Windows Live Messenger ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: msnmsgr.exe; 14.0.8117.416; 4bc935af; wldcore.dll; 14.0.8117.416; 4bc93503; 0; 00002ee5.


Google helped again.  A nickname bouke had found the solution.

I renamed the key UTL -> UTL_ in the registry path HKCU\Software\Microsoft\MSNMessenger\PerPassportSettings\<number>\ and the problem was solved.  My avatar disappeared as a result of this, but it was a small problem.