I'm not sure if this works, but you can try it: - Extract the main EXE, then run pcc.msi with /qn. Or, without extraction, you can run the main EXE with /S /v"/qn". You can use /qn REBOOT=ReallySuppress or /S /v"/qn REBOOT=ReallySuppress" if you know that the app requires your PC to restart. - Use this reg key to register: Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SOFTWARE\TrendMicro\PC-cillin] "register no."="xxxx-####-####-####-####"