Troj_CIADOOR.AS lo_602429674.exe

Hi,
Ihave a pc with WXP Pro. Norton and Trend detect a virus. Norton said it is in the winlogon.exe file. I try to use recovery console and delete the file and expand another copy using winlogon.ex_ off the install disk. It does not appear to del the original because when I look at properties it said created today at 12:30 even though I del it many times. How can I delete the system file winlogon.exe?