What I mean is that with my installer I have the same problem that RedBeard1971 reported, but solved by adding the key
Code:
Root: HKLM; Subkey: SOFTWARE\Bethesda Softworks\Fallout3; ValueType: string; ValueName: "Installed Path"; ValueData: "{app}"; Flags: uninsdeletekey;
the PLAY option in the launcher is available, but when clicked it shows the following message: "Fallout 3 does not appear to be installed and the installer could not be found".
My question is, what registry keys or settings did you change to fix this problem?