Computer Black Screen; no menus, or toolbars.

To whom it may concern,

I was on the Internet late night (again) and after clicking a link a friend posted on facebook to another social website "formspring" a pop-up came up and I thought nothing of it, and would continuously "x" out of all of them. after a little while my security wall freaked out, but I continued to close out of it. After a little while of that, a larger pop-up came stating something was trying to get my passwords for various sites. so I shut my computer off.
This morning I turn on my computer and all I get is a black screen. No toolbars, icons, or anything ! It'll open Internet searching or things. My hot keys don't effect this, and I can't access any "my computer" type of programs. Help is appeticated.