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1: Problem: Do I need to register the Half Life product before playing the game?
Solution:
Product registration is not required to play the Half Life 2 program, and this option can be cancelled.
However, you must still authenticate the Half Life 2 CD key through Steam before initiating the game for the first time.
2: Problem: User is encountering an invalid CD key error when authenticating his/her key for Half Life 2 with Steam
Solution:
If you are receiving an invalid CD key error during the authentication process with the Half Life 2 program,
please make certain that you are entering the key exactly as it is displayed on the packaging for the product.
This should only consist of 5 groups of 5 letters and numbers.
Please note that you must include the dashes between the letter/number groups in the key.
Also, if you have the version of HL2 that comes on the 5 CD`s (standard version),
you should only enter the information on the first line from the back of the disk
envelope for CD #1 (See example below):
Example text on back of envelope for Disk #1:
Key#: 5AB34-1234A-2ABCD-XYZ3X-A2B34 --> Complete CD key
S7160880 HALFLIFE 2 --> Do not enter any information from this line -- S7160880 is not part of the key code
3: Problem: If during the initial installation process the option to install “Counter-strike: Source” is NOT selected, an error may occur during installation. The message will be: cabinet file error, fatal disk error, or something similar.
Solution:
Cancel the current installation process and reinstall the game from the beginning, starting with Disk #1. Make certain to select the option to install both Half-Life 2 and Counter-strike: Source.
Note: If you prefer not to retain the Counter-strike: Source program on your system AFTER INSTALLATION, you can remove it using the following procedure:
1. After HL2 has been successfully installed open up the Steam client.
2. Select the Play Games list
3. RIGHT click on Counter-strike: Source and select Properties
4. Select “Delete Local Content.”