I think I got a clickjacking virus. Will this affect my computer, or just my Facebook?

[♪♫♥ℓunα★♫]

If it will affect my computer, is there a free virus protection thing that I can get for a Mac?
Yeah, it is on my Facebook, because I'll see random pages that I didn't "like" on my newsfeed, and I didn't put them there. My computer's not acting weird at all, but I thought it'd be best to ask since I don't know much about the virus.

[Matt]

I thought Macs were immune to viruses...

...whoops.

Just kidding, but I'm serious. Anyway, it wouldn't affect your Facebook account; Facebook profiles don't get viruses. What makes you think your computer is actually infected?

Edit: That sounds to me like someone else is actually using your account, not that it has some sort of infection on it. Change your password ASAP.