So... You have several options. First one is the registry edit:
its simple follow these steps
1.On your windows machine click on start and in the (Search for programs and files) box type in regedit and open regedit.exe
2. Next click on the little arrow next to the folder named HKEY_LOCAL_MACHINE and make your way to ergc directory the full path is
HKEY_LOCAL_MACHINE -> SOFTWARE -> Wow6432Node -> Electronic Arts -> EA Games -> Command and Conquer Generals Zero Hour -> ergc
Note: If you cannot find Wow6432Node then ignore it and procees to Electronic Arts -> EA Games Command and Conquer Generals Zero Hour -> ergc. Thanks to Khalilz for pointing this out.
3. Click on the ergc directory and right click on Default (located on the right side under Name) and Modify it.
4. Now simply add the - between the serial numbers.Write it exactly how its written on the game you bought. if you notice It only displays your serial number without the - between the code so you will just need to add them in
for example change it from 123A5678B8CDD3D3P0P0 to 123A-5678-B8CD-D3D3-P0P0 now try playing the same you should be able to play it online
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If you try playing and your buildings blow up 30 seconds into the game there is another fix for this.
This is a built in feature EA added to help prevent anti-piracy
[Make sure you read the steps above then continue reading this]
Have the regedit open on ergc directory copy the serial that you have modified (the serial number that you included with the -) and uninstall zero hour keeping the regedit still open on the ergc directory.
Now heres the trick, we will need to reinstall zero hour BUT as it is installing zero hour we quickly replace the registry with the modified serial number that included the dash's. So put the CD in and start up the installation process when it will prompts you for the serial number type the serial number as you normally would and as soon as you put the serial number click next and stop there, dont install zero just yet!
Now go to the opened regedit.exe and click on ergc directory using and modify the default registry key by adding the dashs in the serial key. And then proceed installing zero hour. this will help bypass the built in anti-piracy glitch and it will work!
If that doesn't work then you'll have to contact EA customer support again. It's a pain, I know, but that's life...
