Ive got a dell laptop not too old bought it second hand from some guy local to me for £100 came freshly installed with service pack 3 had it a few months its been fine, then earlier it said windows update available so i installed the update, restarted the computer, won't let me log onto eBay now, facebook, lets me on the car websites, and ive got a blue star in the taskbar saying ' validation failure ' ive clicked the star it opens a screen up on the windows website and theres a button that says resolve now, i click that and i just get a blank white internet screen..?

Any ideas?