recently, i have been receiving a lot of junk email in my email account which happen to all the user on my computer too. It have the title of "hi" or "information" Similarly, i have also received email from the postmaster which tell me that my email with similar title is not received by others. I did not send out these emails and my computer was not even switched on at the time and date the email was claimed to be sent out. I thought that i may have been infected with the netsky virus. so i download the netsky virus removal from symatec but nothing is found. Simlilarly, i run my mcaffee anti-virus and nothing is found. What is happening? Am i infected with a virus?

They are spoof, especially the postamster "returns", which I assume all come with a convenient attached "copy of your offending email" for you to examine? Just delete them all without opening. If there is anything genuine amongst them, the sender will ask you why you never responded and resubmit it. Since my ISP mailbox is my oldest and most published, I now have a policy of killing everything sent to it on sight and unread. I use a remote mail server query to do it at arm's length right on the server, so nothing ever touches my own machine. If anything real is among the killed stuff.... tough, they should be using the official covert contact point I have established for genuine friends to reach me. That is how I handle the crap in the world today, as the risks are too great to show mercy. I strongly urge you to do the same.