Problem with downloading mods for portal!

[Leafcathead™]

When ever I try to download a mod for portal I am greeted with a white screen and a error message that says materials/console/startup_loading.vtf the mod I was trying to install was Hetzchase Nailway.

[ertesda]

Try to move that file to your desktop. Then start steam again or let it check the game files. It will download the file and then you can play the game. At least I think so.