Hi Richard,
the pb occurred at 3AM w/o any human intervention.
The next morning, the client has been restarted ... many backups have been 
scheduled every night since then ... no problem ... but I would like to know 
what happens, just in case it reoccurs !
The client on which it occurs does not know about TRACE commands. So, he can't 
have issued such commands.

Thanks a lot,

Pascal.