I managed to fix it. First, I deleted the local content on steam. Then I went into the steamapps folder and manually deleted the NS2 folder there. Reinstalled and now it's working fine.
Same problem. I've deleted and reinstalled twice, now.
Also, the console will open. I'm not sure if this means anything. I'm not a programmer or anything, so I've no idea what any of it means. So I can't comment on it working or not.