A few minutes ago, while converting some avi files, a box opened up in the middle of my screen with the message "You are about to be logged off. Windows will close down in less than 5 minutes". A minute or so later I was logged off and the conversion was ruined. I've never seen a message like this before and wonder if anybody on these forums can tell me what caused it. I have Googled the message but did not see anything relevant. I'm using Windows 7 Ultimate and my laptop has started up again without any problem. Thanks.