Crashed upon creating game in Counter-Strike: Source?

I just bought the cd, and it runs fine when I connect to an online server. But, when I create a game and play with bots, the screen hangs at "loading resources", then exits to desktop with the following error: The instruction at "0x05a53e2c" referenced memory at "0x0d7aa1a0". The memory could not be "read". Click OK to terminate the program. My other Steam games like Half-Life, Opposing Force and Blue-Shift works fine as well. Even Half-Life 2. So I'm just plain puzzled. Any help would be appreciated.