"Frequency out of range"?

What would cause the game to suddenly start doing this? I've played it since launch, and it was worked fine. Now suddenly when I try to load it, it tells me that. was there a patch recently that ****ed with the settings or something?

and how I do I change the settings without going into the game, which I can't do?

found a setting in properties in the steam folder that let me tell it to launch at a specific resolution. it works then. but I get a message saying my settings are not secure, and that I won't be able to connect to VAC servers.