Farm update failure: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server

Yesterday, during a tentative to install SP1 on customer farm, I received a really stressfull failure message (below record on Upgrade.log): ======================================================================== [PSCONFIG] [SPManager] [INFO][8/22/2011 7:38:18 PM]: Upgrade Boot Strap starts. Initialized in Mode:InPlace, as MachineAdmin: True. [PSCONFIG] [SPManager] [DEBUG] [8/22/2011 7:38:18 PM]: Detected v4 configuration database dsn: DataSource='”ColSQL08Web                  “‘;Initial Catalog=SharePoint_Config;Integrated Security=True;ConnectTimeout=15;Application Name=”Microsoft SharePoint Foundation”. [PSCONFIG]…