ok this came up on my screen twice while i'm online the last 2 days. there's a pop up download from window xp started scanning my computer saying it detected a virus on my computer and asked if i want to remove it. i had bad experienced with similar pop up before so i don't trust it. i click cancel, but it went ahead and started scanning my computer, ? the pop up had window xp logo and trade mark just like the real thing. i do scan my pc regulary, but nothing saying i have a virus. is this safe to download?