Quake 4 Problem with invalid Serial

[Executor55]

Quote of the Deviance .nfo:
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Install notes:
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1) Unrar
2) Burn or mount
3) Install using the following serial: ...
4) Copy the crack from the DEViANCE dir on the DVD into game dir
5) Block internet connection from quake4.exe with your firewall
6) Play
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When I launch the Game I get a hint: CD key Invalid.

What can I do if I don't have a firewall and don't want to install one?

Which program can block an internet connetion to one .exe file?
Is this possible?

Please Help!