> '09:59:28 Error:  'Acesso negado' (401) at link 
> user:password@www.site.com.br:81/index.htm (from 
> primary/primary)

Hum - the site may require challenged authentication, this 
might be the cause. (I double-checked the authentication 
routines, and the "Basic auth" seems to be ok)
It is also possible that offline browsers be filtered.