Steam Error: 1335 the cabinet file .cab required for this installation is corrupt and cannot be used

http://support.steampowered.com/cgi-bin/steampowered.cfg/php/enduser/std_adp.php?p_faqid=293

If you are getting an error during the installation of your HL2 cd/dvd please exit the installer and run Steam on it's own. There were changes made to the installer files after the cd/dvds were printed that requires an update from Steam. Once Steam has finished downloading it's update you can exit and run the installer again without recieving the error.

If you are unable to get past this then you should return the package to the store for an exchange or see the Contacting VALVe Billing and Support article to create a support case. Once we recieve your case we will provide you with instructions on obtaining a new cd.