For all I know, everything could be fine with my computer just that today, I windows popped up that made me suspicious. If I can recall correctly, after running a Norton Antivirus Scan, it read 2 threats. One was successfully cleaned and repaired, and the other required rebooting to take effect. And I was about to, and this window came up asking me to enter the code displayed on a image to make sure that the computer I was using was mine. I found this quite strange, and even stranger was the fact that it was the kind of image that comes up in forums when registering (such as this one) to make sure you aren't a spam bot. Also, it was the 'Always stay on top' windows, so I couldn't close it with Windows Task Manager because of that. It had no 'Cancel' button, and the only button was the OK one which I'm guessing I'm supposed to press after entering the code. Which I did not, as I suspected it was a some kind of keylogger or other type of Malware. I then rebooted my computer as Norton suggested and it was gone.
I took the precation of running another Security Scan (everything fine) and going to my Command Box and entered the follwing as recommended by someone who helped me in another thread of mine, Jelly Bean (thanks for your help, everything's fine now

) sfc /scannow.
So far, nothing has happened out fo the usual. Should I be worried? Has this happened to anyone else?
Thanks in advance. Simps.