Win7Internet Security 2012 has locked me out

Hello, I've read through all the other posts about Win 7 Security 2012, but this virus has completely shut me out of my computer in a matter of half an hour. When I turn my computer on, the windows (I have windows 7) log in screen appears, I log in, then a black screen with the Win7 Secuity messages pop up. I cannot get past them, and upon cancelling the windows, the screen simply remains black. I cannot even get to my desktop. Please help, other posts had not mentioned this type of sickness.