Yeah - that wasn't your computer screen; it was a web screen modified to LOOK like your computer screen.
Look closely next time, and don't click on ANYthing that says "free virus scan" "free adware/malware scan"
There is NO such thing as a free online malware/adware scan. You are simply being duped into downloading an exe file which will eventually either install a virus into your machine, or harvest your personal information and send it back to wherever it came from.
The ONLY solution to these simple problems is to use Linux. It's free, available for 90% or more of all currently available systems (including Macs!) and it is virtually virus-free.
I say "virtually" because you can probably install viruses on the emulators for more common OS's.
It's not as hard as it sounds. Go to www.ubuntu.com to find out more.
The common misrepresentations of Linux/unix systems give them a bad rep, but nowadays you can rip/burn music and dvd's, play games, render graphics, make movies, and everything on this operating system, just as well - sometimes better - than Windows or Mac OS.