Did you follow the links I gave?
From that specfic link there was
http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/2c522246-8450-408d-b907-197dfa0fdbb6.mspx?mfr=true
about installing Frontpage extension, how they were install previously, Running them as applications, etc, etc
Have you gone through that and understood it?
Why don't you Re-installed and re-enabled the FPEs.