I tried to go to the website wikipedia.org but I made a typo and I think I typed "wwikipedia.org" instead and I was sent to a site with a blank page and at the top of the page I think it said firefox blocked a pop-up. I did a comprehensive virus scan and a quick virus scan and nothing turned up. I would have left it at that but my PC began acting strangely several hours later -- I was unable to start any programs or even restart. I click the icons and nothing happened. Eventually the PC restarted but it sort of froze and there was a black screen and in the middle there was a white box with the text "security logon failed" or something similar to that.The PC works fine now but I am still worried that I may have a virus.
Do the things that I mentioned indicate a possible virus or keylogger? Should I do a system restore, or is there no need to worry about it?
Thanks