in the Console , SQL Server Configuration Manager

I get error 10048 when start sql service

and this in event history:

The SQL server service terminated with server-specific error. Only one usage of each socket (protcol/network address/port) is normall permitted. Any idea howto fix this ? Port set is the default 1433... If this is turned off, which is default of course, SQL service starts like a champ. I have done this config many times on other servers with no problem.