Microsoft informs that if you've installed TMG 2010, but when running the Getting Started wizard, you get the following error (see pic below), when choosing the Network Template:
It's seen on servers where Operating System hardening has been applied prior to TMG installation. As a result, some services required by TMG to operate properly have been wrongly disabled causing the problem described above.
"The solution and only supported way to perform hardening of a TMG machine is to execute the Security Configuration Wizard (SCW) tool and use TMG security configuration template (XML file) matching your deployment in order to harden properly the server," explains Microsoft.
Note: By default, SCW doesn't include support for TMG 2010 role nor TMG Enterprise Management Server (EMS) role. To support these roles, download and install TMGRolesForSCW.exe included in TMG 2010 Tools and Software Development Kit (SDK).