[Nordek]

Dodakaedr, В разделе HKEY_CLASSES_ROOT лучше не менять ассоциацию.
Лучше так:

Код:

[Registry]
Root: HKCU; Subkey: Software\Classes\.mp3; ValueType: string; ValueName: ; ValueData: Kallisto.enqueue; Flags: uninsdeletevalue
Root: HKCU; Subkey: Software\Classes\Kallisto.enqueue\DefaultIcon; ValueType: string; ValueName: ; ValueData: {app}\Kallisto.dll,2; Flags: uninsdeletevalue
Root: HKCU; Subkey: Software\Classes\Kallisto.enqueue\shell\open\command; ValueType: string; ValueName: ; ValueData: "{app}\Kallisto.exe ""%1"""; Flags: uninsdeletevalue

Или так:

Код:

[Registry]
Root: HKLM; Subkey: Software\Classes\.mp3; ValueType: string; ValueName: ; ValueData: Kallisto.enqueue; Flags: uninsdeletevalue
Root: HKLM; Subkey: Software\Classes\Kallisto.enqueue\DefaultIcon; ValueType: string; ValueName: ; ValueData: {app}\Kallisto.dll,2; Flags: uninsdeletevalue
Root: HKLM; Subkey: Software\Classes\Kallisto.enqueue\shell\open\command; ValueType: string; ValueName: ; ValueData: "{app}\Kallisto.exe ""%1"""; Flags: uninsdeletevalue

P.S