asterisk users - Jan 2008 - Loosing IAX/SIP user's registration

Hello list, hope some one could help me find the answer.

Asterisk 1.4.16.2 installd as non-root user

The main issue is that every now and then, cd * box seems to loose the
user's registrations, there is nothing in the console, absolutely no
messages, only when another friend trys to dial an extension I can see this
on messages logs