In \Windows folder I found file name Œ÷t dated 2010-03-20 08.44, 1K size; content: [KeyList]Count=0 Security Essentials does not react to it.There are no other files in \Windows or \Windows\System32 of similar date time. Google search finds nothing equal. Never having seen one before, I don't even know what a Œ is.

I suggest you try a free online virus scan on the following site: http://safety.live.com/ Meanwhile, if you need more help with virus-related issues, please contact Microsoft Product Support Services. For support within the United States and Canada, call toll-free (866) PCSAFETY (727-2338). For support outside the United States and Canada, visit the Product Support Services Web page (<http://support.microsoft.com/?pr=SecurityHome> ). If you believe this is a false nagetive issue, you can also post it in Microsoft Security Essentials forum via the following link: http://social.answers.microsoft.com/Forums/en/msestart/threads Hope this helps!Sean Zhu - MSFT