Forum Post: Error installing NAV Web Server Instance

I get this error when trying to install the Web Server Components:

CAQuietExec64:  New-NavWebServerInstance : A Microsoft Dynamics NAV Web Server Instance

CAQuietExec64:  already exists.

CAQuietExec64:  At C:\Program Files\Microsoft Dynamics NAV\71\Web

CAQuietExec64:  Client\Bin\WebServerInstance.ps1:45 char:1

CAQuietExec64:  + New-NavWebServerInstance @arguments

CAQuietExec64:  + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

CAQuietExec64:      + CategoryInfo          : NotSpecified: (0:Int32) [New-NAVWebServerInstanc

CAQuietExec64:     e], NavCommandException

CAQuietExec64:      + FullyQualifiedErrorId : DynamicsNAV71,Microsoft.Dynamics.Nav.Management.

CAQuietExec64:     Cmdlets.NewNavWebServerInstance

CAQuietExec64:  

CAQuietExec64:  Error 0x80070001: Command line returned an error.

CAQuietExec64:  Error 0x80070001: CAQuietExec64 Failed

CustomAction CreateWebApplication returned actual error code 1603 (note this may not be 100% accurate if translation happened inside sandbox)

Action ended 12:41:23: InstallFinalize. Return value 3.

Any idea?

Thanks in advance!